Update FUNDING.yml to enable github/alexellis

Detail was removed on 10th June with a comment that it will be enabled once GitHub provide access to the beta.  This access was provided on 12th June hence re-enabling.

Signed-off-by: Richard Gee <richard@technologee.co.uk>

.github/FUNDING.yml

 # For more - see https://www.openfaas.com/support/
 
-# When GitHub grants me access to the beta, I'll uncomment the below
-#github: alexellis
-
+github: alexellis
 patreon: alexellis
 community_bridge: openfaas
 custom: https://paypal.me/openfaas?locale.x=en_GB