README: fix menu item name capitalization

The text of the action in the resources bundle is already correct.  Fix
the mention of the menu item in the plugin description in README.md.

For reference, here's a quote from IntelliJ Platform UI Guidelines:

> Capitalization
>
> Title
>
> Use for:
>
>   - Actions in buttons, menus and tooltips
>   - Headers in tables, popups, message boxes and dialogs
>   - Headers of UI control groups
>
> Rules
>
> Always capitalize the first and the last words.
> Capitalize the words in-between except:
>
>   - articles: a, an, the,
>   - coordinating conjunctions: and, or, but,
>   - prepositions of four and less letters which are not a part of a
>     phrasal verb: in, with.

https://jetbrains.design/intellij/text/capitalization/

README.md

@@ -23,7 +23,7 @@ See [LICENSE.txt](LICENSE.txt) for details.
       `CopyRevisionNumberFromAnnotateAction`
 
 <!-- Plugin description -->
-Provides a context menu item "Copy commit reference" in all VCS log views. It copies a reference to the commit in
+Provides a context menu item "Copy Commit Reference" in all VCS log views. It copies a reference to the commit in
 the [same format as `git log --format=reference`](https://git-scm.com/docs/git-log#_pretty_formats).
 <!-- Plugin description end -->
 

src/main/resources/messages/CopyCommitReferenceBundle.properties

@@ -1,2 +1,3 @@
+# Title Case Capitalization as per https://jetbrains.design/intellij/text/capitalization/
 action.devAndrybakCopyCommitReferenceAction.text=Copy Commit Reference
 action.devAndrybakCopyCommitReferenceAction.description=Copy a reference to the commit into the clipboard