matrix: trusted_key_servers/suppress_key_server_warning

matrix-1  | This server is configured to use 'matrix.org' as its trusted key server via the
matrix-1  | 'trusted_key_servers' config option. 'matrix.org' is a good choice for a key
matrix-1  | server since it is long-lived, stable and trusted. However, some admins may
matrix-1  | wish to use another server for this purpose.
matrix-1  | 
matrix-1  | To suppress this warning and continue using 'matrix.org', admins should set
matrix-1  | 'suppress_key_server_warning' to 'true' in homeserver.yaml.
matrix-1  | --------------------------------------------------------------------------------