doc: pretty up return code table for sync_aggregates
doc: pretty up return code table for sync_aggregates

This just changes the bullet format to a more appealing
table format and is consistent with the other commands
in here that use a table format for documenting return
codes.

Change-Id: I427e64f49f152231810ca48908f1ceff5b8a41d9

klmitch/nova,rahulunair/nova,openstack/nova,openstack/nova,rahulunair/nova,openstack/nova,mahak/nova,klmitch/nova,klmitch/nova,klmitch/nova,rahulunair/nova,mahak/nova,mahak/nova