Buck: Add support for groups of acceptance tests

The number of acceptance tests and the time consuming to run it growing.
To optimize this, this change uses Buck's feature to label a group of
tests.  Currently the following groups are supported:

* api
* git
* pgm
* rest
* server
* ssh

To run only some of groups, the following command can be executed:

  buck test --all --include api rest

To exclude specific groups, the following command can be executed:

  buck test --all --exclude git ssh

Change-Id: Ic339f76654ff60dfc0976a14a12bcea7313c7eef
diff --git a/Documentation/dev-buck.txt b/Documentation/dev-buck.txt
index 33c4e9f..7470dcc 100644
--- a/Documentation/dev-buck.txt
+++ b/Documentation/dev-buck.txt
@@ -283,6 +283,21 @@
   buck test --all --exclude slow
 ----
 
+To include a specific group of acceptance tests:
+
+----
+  buck test --all --include api
+----
+
+The following groups of tests are currently supported:
+
+* api
+* git
+* pgm
+* rest
+* server
+* ssh
+
 To run a specific test, e.g. the acceptance test
 `com.google.gerrit.acceptance.git.HttpPushForReviewIT`: