Explain when to add admins and ops with accessbot

We're happy for teams to manage their individual IRC channel access
lists through our accessbot configuration if they want, so explain
the situations in which they might choose to add channel ops or
admins, and the differences between them.

Change-Id: I4ae4463fe5017176d2d93cbaac6820fe11350899

doc/source/irc.rst

@@ -243,14 +243,19 @@ Accessbot
 =========
 
 Accessbot defines access that should apply to all channels. Teams can add new
-channel to accessbot/channels.yaml and optionally set additional channel admins
-or ops, or specific mode overrides:
+channels to accessbot/channels.yaml and optionally set additional channel
+admins or ops, or specific mode overrides.
 
-Accessbot's configuration is in :config:`accessbot/channels.yaml`
+For typical day-to-day actions like updating channel topics or banning
+disruptive users, volunteer ops are sufficient. If the team wishes to retain
+deeper control over channel settings which aren't handled via accessbot, then
+having some volunteer admins can occasionally be useful. In either case, our
+global volunteers are also happy to assist with any of these activities, so
+feel free to ask for help in the #opendev channel.
 
-Example:
+Accessbot's configuration is in :config:`accessbot/channels.yaml`
 
-::
+Example::
 
   - name: foo
     mode: +bar