Fix a typo and fix section naming in docs

docs/source/tech_storage.rst

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+.. _a_storage:
+
+******************
+How Data is Stored
+******************
+
+This section contains details of how novelWriter stores and handles the project data.
+
+
+Project Structure
+=================
+
+All novelWriter files are written with utf-8 encoding. Since Python automatically converts Unix
+line endings to Windows line endings on Windows systems, novelWriter does not make any adaptations
+to the formatting on Windows systems. This is handled entirely by the Python standard library.
+Python also handles this fairly well when working on the same files on both Windows and Unix-based
+operating systems.
+
+
+Main Project File
+-----------------
+
+The project itself requires a dedicated folder for storing its files where novelWriter will create
+its own "file system" where the folder and file hierarchy is described in a project XML file. This
+is the main project file in the project's root folder with the name ``nwProject.nwx``. This file
+also contains all the meta data required for the project, and a number of related project settings.
+
+If this file is lost or corrupted, the structure of the project is lost, although not the text
+itself. It is important to keep this file backed up, either through the built-in backup tool, or
+your own backup solution.
+
+.. tip::
+   The novelWriter project folder is structured so that it can easily be added to a version control
+   system like git. If you do so, you may want to add a `.gitignore` file to exclude files with the
+   extensions `.json` as JSON files are used to cache the index and various run-time settings and
+   are generally large files that change often. You'd also want to exclude the ``cache`` folder.
+
+The project XML file is indent-formatted, suitable for diff tools and version control since most of
+the file will stay static, although a timesetamp is set in the meta section on line 2, and various
+meta data entries incremented, on each save.
+
+
+Project Documents
+=================
+
+All the project documents are saved in a folder in the main project folder named ``content``. Each
+document has a file handle taken from the first 13 characters of a SHA256 hash of the system time
+plus an incremented number when the document was first created. The documents are saved with a
+filename assembled from this hash and the file extension ``.nwd``.
+
+If you wish to find the file system location of a document in the project, you can either look it
+up in the project XML file, select :guilabel:`Show File Details` from the :guilabel:`Document` menu
+when having the document open, or look in the ``ToC.txt`` file in the root of the project folder.
+The ``ToC.txt`` file has a list of all documents in the project, referenced by their label, and
+where they are saved.
+
+The reason for this cryptic file naming is to avoid issues with file naming conventions and
+restrictions on different operating systems, and also to have a file name that does not depend on
+what the user names the document within the project, or changes it to.
+
+Each document file contains a plain text version of the text from the editor. The file can in
+principle be edited in any text editor, and is suitable for diffing and version control if so
+desired. Just make sure the file remains in utf-8 encoding, otherwise unicode chatracters may
+become mangled when the file is opened in novelWriter again.
+
+Editing these files is generally not recommended outside of special circumstances, whatever they
+may be. The reason for this is that the index will not be automatically updated when doing so,
+which means novelWriter doesn't know you've altered the file. If you do edit a file in this manner,
+you should rebuild the index when you next open the project in novelWriter.
+
+The first lines of the file may contain some meta data starting with the characters ``%%~``. These
+lines are mainly there to restore some information if it is lost from the project file, and the
+information may be helpful if you do open the file in an external editor as it contains the
+document label and the document class and layout. The lines can be deleted without any consequences
+to the rest of the content of the file, and will be added back the next time the document is saved
+in novelWriter.
+
+
+The File Saving Process
+-----------------------
+
+When saving the project file, or any of the documents, the data is first saved to a temporary file.
+If successful, the old data file is then removed, and the temporary file becomes the new file. This
+ensures that the previously saved data is only replaced when the new data has been successfully
+saved to the storage medium.
+
+For the project XML file, a ``.bak`` file is in addition kept, which will always contain the
+previous version of the file, although when auto-save is enabled, they may have the same content.
+If the opening of a project file fails, novelWriter will automatically try to open the ``.bak``
+file instead.
+
+
+Project Meta Data
+=================
+
+The project folder contains a subfolder named ``meta``, containing a number of files. The meta
+folder contains semi-important files. That is, they can be lost with only minor impact to the
+project.
+
+If you use version control software on your project, you can exclude this folder, although you may
+want to track the session log file. The JSON files within this folder can safely be ignored as they
+will be automatically regenerated if lost.
+
+
+The Project Index
+-----------------
+
+Between writing sessions, the project index is saved in a JSON file in ``meta/tagsIndex.json``.
+This file is not critical. If it is lost, it can be rebuilt from within novelWriter from the
+:guilabel:`Tools` menu.
+
+The index is maintained and updated whenever a document or note is saved in the editor. It contains
+all references and tags in documents and notes, as well as the location of all headers in the
+project, and the word counts within each header section.
+
+The integrity of the index is checked when the file is loaded. It is possible to corrupt the index
+if the file is manually edited and manipulated, so the check is important to avoid sudden crashes
+of novelWriter. if the file contains errors, novelWriter will automatically build it anew. If the
+check somehow fails and novelWriter keeps crashing, you can delete the file manually and rebuild
+the index. If this too fails, you have likely encountered a bug.
+
+
+Cached GUI Options
+------------------
+
+A file named ``meta/guiOptions.json`` contains the latest state of various GUI buttons, switches,
+dialog window sizes, column sizes, etc, from the GUI. These are the GUI settings that are specific
+to the project. Global GUI settings are stored in the main config file.
+
+The file is not critical, but if it is lost, all such GUI options will revert back to their default
+settings.
+
+
+Session Stats
+-------------
+
+The writing progress is saved in the ``meta/sessionStats.log`` file. This file records the length
+and word counts of each writing session on the given project. The file is used by the
+:guilabel:`Writing Statistics` tool. If this file is lost, the history it contains is also lost,
+but it has otherwise no impact on the project.
+
+
+Project Cache
+=============
+
+The project ``cache`` folder contains non-critical files. If these files are lost, there is no
+impact on the functionality of novelWriter or the history of the project. It contains temporary
+files, like the preview document in the :guilabel:`Build Novel Project` tool.
+
+It should be excluded from version control tools if such are used.