Capitalize 'VCS' in tree-view config settings.

:lipstick: Capitalize 'VCS' in tree-view config settings.

this matches main Atom settings panel and the fix here is the same done for that settings panel as seen by this commit: https://github.com/atom/atom/commit/a12fb94d77c3bcdad7b0ef0098a32a6b740d1b67

Thanks.