Document features of the code-owners plugin on the about page

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Iafae132554101586447e6c79cae597b3d93e48a4

resources/Documentation/about.md

diff --git a/resources/Documentation/about.md b/resources/Documentation/about.md
index 6126097..d558de6 100644
--- a/resources/Documentation/about.md
+++ b/resources/Documentation/about.md
@@ -16,3 +16,55 @@
 for code owners is pretty generic and [configurable](config.html) so that it
 should be suitable for other teams as well.
 
+## <a id="functionality">Functionality
+
+* Support for defining code owners:
+    * Code owners can be specified in `OWNERS` files that can appear in any
+      directory in the source branch.
+    * Default code owners can be specified on repository level by an `OWNERS`
+      file in the `refs/meta/config` branch.
+    * Global code owners across repositories can be configured.
+    * A fallback code owners policy controls who owns files that are not covered
+      by `OWNERS` files.
+    * Code owners can be specified by email (groups are not supported).
+    * Inheritance from parent directories is supported and can be disabled.
+    * Including an `OWNERS` file from other directories / branches / projects is
+      possible (only on the same host).
+    * File globs can be used.
+    * see [code owners documentation](config-guide.html#codeOwners) and
+      [OWNERS syntax](backend-find-owners.html#syntax)
+<br><br>
+* Prevents submitting changes without code owner approvals:
+    * Which votes count as code owner approvals is
+      [configurable](setup-guide.html#configureCodeOwnerApproval).
+    * Implemented as Java submit rule (no Prolog).
+<br><br>
+* Support for overrides:
+    * Privileged users can be allowed to override the code owner submit check.
+    * Overriding is done by voting on a [configured override
+      label](setup-guide.html#configureCodeOwnerOverrides).
+    * see [override setup](config-faqs.html#setupOverrides)
+<br><br>
+* UI extensions on change screen:
+    * Code owner suggestion
+    * Display of the code owners submit requirement
+    * Display of code owner statuses in the file list
+    * Change messages that list the owned paths.
+    * see [UI walkthrough](how-to-use.html) and [user guide](user-guide.html)
+<br><br>
+* Extensible:
+    * Supports multiple [backends](backends.html) which can implement different
+      syntaxes for `OWNERS` files.
+<br><br>
+* Validation:
+    * updates to `OWNERS` files are [validated](validation.html) on commit
+      received and submit
+    * `OWNERS` files can be validated on demand to detect consistency issues
+<br><br>
+* Rich REST API:
+    * see [REST API documentation](rest-api.html)
+<br><br>
+* Highly configurable:
+    * see [setup guide](setup-guide.html), [config-guide](config-guide.html),
+      [config FAQs](config-faqs.html) and [config documentation](config.html)
+