[rubygems/rubygems] Generalize description to account for different push servers

https://github.com/rubygems/rubygems/commit/cbf13edd3a

lib/rubygems/commands/owner_command.rb

@@ -15,6 +15,10 @@ The owner command lets you add and remove owners of a gem on a push
 server (the default is https://rubygems.org). Multiple owners can be
 added or removed at the same time, if the flag is given multiple times.
 
+The supported user identifiers are dependant on the push server.
+For rubygems.org, both e-mail and handle are supported, even though the
+user identifier field is called "email".
+
 The owner of a gem has the permission to push new versions, yank existing
 versions or edit the HTML page of the gem.  Be careful of who you give push
 permission to.
@@ -36,11 +40,11 @@ permission to.
     add_otp_option
     defaults.merge! :add => [], :remove => []
 
-    add_option '-a', '--add NEW_OWNER', 'Add an owner by email or handle' do |value, options|
+    add_option '-a', '--add NEW_OWNER', 'Add an owner by user identifier' do |value, options|
       options[:add] << value
     end
 
-    add_option '-r', '--remove OLD_OWNER', 'Remove an owner by email or handle' do |value, options|
+    add_option '-r', '--remove OLD_OWNER', 'Remove an owner by user identifier' do |value, options|
       options[:remove] << value
     end