Add job's project as implicit role project

Add the project in which a job is defined as an implicit role project.
This is a convenience for job authors who may want to put roles in
the root of the project (ie, not adjacent to job playbooks, since,
after all, the roles may be useful outside of the job playbooks).  In
that case, they will not need to specify the job's own project in the
roles: section of the job.

Change-Id: Ia382c2da9f7eb7139ceb0b61cb986aace8dc8d8f
diff --git a/doc/source/user/config.rst b/doc/source/user/config.rst
index 76f73c3..c4f09de 100644
--- a/doc/source/user/config.rst
+++ b/doc/source/user/config.rst
@@ -738,6 +738,12 @@
   be installed (and therefore referenced from Ansible), the `name`
   attribute may be used to specify an alternate.
 
+  A job automatically has the project in which it is defined added to
+  the roles path if that project appears to contain a role or `roles/`
+  directory.  By default, the project is added to the path under its
+  own name, however, that may be changed by explicitly listing the
+  project in the roles list in the usual way.
+
   .. note:: galaxy roles are not yet implemented
 
   **galaxy**