Cross-wiki notifications

[Matthew Flaschen]

I spoke to Riccardo at FOSDEM, and he indicated you might be interested 
in setting up cross-wiki notifications.

There is not much documentation right now 
(https://phabricator.wikimedia.org/T125728).  But basically you need to 
run db_patches/echo_unread_wikis.sql (in Echo repo) in a shared database 
(that all wikis can access).

Then, set $wgEchoSharedTrackingDB and $wgEchoSharedTrackingCluster 
appropriately.

Also set $wgEchoUseCrossWikiBetaFeature to true if you want it to be a 
Beta Feature (requires BetaFeatures extension) (probably a good idea to 
make it a BetaFeature initially while we iron out any issues).

Matt Flaschen