Doc team notifications of freeze breaks

Hi,

Historically, our rules for freezes have required notifying 
gnome-doc-list@ of any freeze breaks. This rule has not always been 
followed (I'm a flagrant violator myself). Since nowadays documentation 
operates on a longer cadence (generally years rather than months), I 
think it really doesn't make sense to have these notifications anymore. 
If there are any recent examples of a documentation change being 
committed within the freeze window in response to a freeze break 
notification, please let me know; otherwise, I don't think this change 
should be controversial.

Also, release team really doesn't need to be involved in string freeze 
breaks (to the extent a string freeze break is not a UI freeze break) 
since the internationalization team is well-qualified to handle these.

This means all freeze break requests can now go to just one place:

 * String freeze break requests go to <[email protected]>
 * Other freeze break requests go to <[email protected]>

unless you're landing a major UI change with string changes, in which 
case you'll still need separate UI freeze and string freeze break 
approvals.

Hopefully this should make freeze break requests a bit easier.