Update documentation

docs/source/project_overview.rst

@@ -118,6 +118,9 @@ The root folders are closely tied to the tags and reference system. Each folder
 the categories of tags that can be used to reference them. For more information about the tags
 listed, see :ref:`a_references_references`.
 
+There is also a ``@mention`` keyword that can be used to reference any tag.
+See :ref:`a_references_references` for more details.
+
 .. note::
    You can rename root folders to whatever you want. However, this doesn't change the reference
    keyword or what they do.

docs/source/project_references.rst

@@ -162,6 +162,12 @@ reference keywords allow multiple values.
    Custom references in the current section. The target must be a note tag in a **Custom** type
    root folder. The custom folder are for any other category of notes you may want to use.
 
+``@mention``
+   Anything mentioned, but not present in the current section. It is intended for those cases where
+   you reveal details about a character or place in a scene without it being otherwise a part of
+   it. This can be useful when checking for consistency later. Any tag in any root note folder can
+   be listed under mentions.
+
 The syntax highlighter will alert the user that the tags and references are used correctly, and
 that the tags referenced exist.
 

docs/source/usage_shortcuts.rst

@@ -165,6 +165,7 @@ a key or key combination for the inserted content.
    ":kbd:`Ctrl+K`, :kbd:`G`",           "Insert a ``@tag`` keyword"
    ":kbd:`Ctrl+K`, :kbd:`H`",           "Insert a short description comment"
    ":kbd:`Ctrl+K`, :kbd:`L`",           "Insert a ``@location`` keyword"
+   ":kbd:`Ctrl+K`, :kbd:`M`",           "Insert a ``@mention`` keyword"
    ":kbd:`Ctrl+K`, :kbd:`O`",           "Insert an ``@object`` keyword"
    ":kbd:`Ctrl+K`, :kbd:`P`",           "Insert a ``@plot`` keyword"
    ":kbd:`Ctrl+K`, :kbd:`S`",           "Insert a synopsis comment"