Introduce StreamEvents capability

This change introduces new global capability for streaming
Gerrit events.

Only admins and users with this capability are able to run
gerrit stream-events.

Change-Id: I0a8a110758b0ac43969e5b8ae799b9b89db318e2
Signed-off-by: Ed Bartosh <bartosh@gmail.com>
Signed-off-by: Alexander Kanevskiy <kad@blackcatlinux.com>
diff --git a/Documentation/cmd-stream-events.txt b/Documentation/cmd-stream-events.txt
index ce23da6..6da0ef0 100644
--- a/Documentation/cmd-stream-events.txt
+++ b/Documentation/cmd-stream-events.txt
@@ -23,7 +23,9 @@
 
 ACCESS
 ------
-Any user who has configured an SSH key.
+Caller must be a member of the privileged 'Administrators' group,
+or have been granted
+link:access-control.html#capability_streamEvents[the 'Stream Events' global capability].
 
 SCRIPTING
 ---------