Update documentation to mention ANGLE committer status and bug editing permissions.

BUG=angleproject:1944

Change-Id: I37d6f22c18e65bd53b75702f0f13ec818b83c34d
Reviewed-on: https://chromium-review.googlesource.com/959224
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

doc/ContributingCode.md

@@ -5,6 +5,7 @@
  * Whether you're writing a new feature or fixing an existing bug, it pays to get a second opinion before you get too far. If it's a new feature idea, post to the discussion group ([angleproject](https://groups.google.com/forum/?fromgroups#!forum/angleproject)) and propose it or talk with the ANGLE team on IRC in the #ANGLEproject channel on FreeNode.
  * Not all bugs in our [bug system](https://bugs.chromium.org/p/angleproject/issues/list) are assigned, but if the one you're interested in fixing is, send a note to the person it's assigned to and ask if they would like a patch.
  * Behavior changes and anything nontrivial (i.e. anything other than simple cleanups and style fixes) should generally be tracked in the bug system. Please [file a bug](http://anglebug.com/new) and describe what you're doing if there isn't one already.
+ * If you would like bug-editing rights, simply ask a team member via email or the disussion group.
 
 ## Get your code ready
 ### Code
@@ -112,6 +113,9 @@ ANGLE has a loose owners structure but the following mapping can be useful for c
  * ChromeOS integration `src/libANGLE/renderer/*/ozone`
    * `fjhenigman at chromium dot org`
 
+### Committer status
+Similar to [Chromium's committer status](https://dev.chromium.org/getting-involved/become-a-committer), long-term contributors to the ANGLE project may request to join the `angle-committers` group.  This allows you to give `+2` on code reviews and land patches without assistance.  After about 6 months of regular contributions, you may request committer status from a core ANGLE team member via email or code review.  Chromium committers may ask at any time.
+
 See also:
 
 * [ANGLE Gerrit](https://chromium-review.googlesource.com/q/project:angle/angle)