Update contributing guide and i18n readme

CONTRIBUTING.md

@@ -25,6 +25,9 @@ either `testing` or `dev` branch.
 * If your contribution is a fix for the latest testing release, branch from the `testing` branch.
 * If your contribution is a new feature, branch from the `dev` branch.
 
+Please do not make your changes on a branch with the same name as any of the above mentioned
+branches. You should make a unique and descriptive branch name in your fork for your changes.
+
 ## Pull Request Process
 
 1. Make sure your code passes all tests and conforms to the style guide. You can check that the

i18n/README.md

@@ -6,6 +6,12 @@ folder at the root of the repository, and the `nw_XX.qm` together with the `proj
 are located in `nw/assets/i18n`. The latter are JSON files translation maps for the novelWriter
 projects, used by the Build Novel Project tool.
 
+**Note**
+
+When making a new translation, or updating an existing one, only commit the `nw_XX.ts` you have
+made changes to. The `qtlupdate` command mentioned below will likely modify all `nw_XX.ts`
+slightly, but please _don't_ commit those changes and add them to the pull request.
+
 ## Qt GUI Localisation
 
 The `.qm` files are the actual files used by the application to translate the GUI into another