Rephrase LDAP check script output

The previous phrasing lead some people to believe that there is a limit
on the number of LDAP users that can sign in to a GitLab instance. That
is not the case; the limit in the check script only applies to the
diagnostic information result set, so that running `rake gitlab:check`
does not output thousands of LDAP users.

lib/tasks/gitlab/check.rake

@@ -698,7 +698,7 @@ namespace :gitlab do
     end
 
     def print_users(limit)
-      puts "LDAP users with access to your GitLab server (limit: #{limit}):"
+      puts "LDAP users with access to your GitLab server (only showing the first #{limit} results)"
       ldap.search(attributes: attributes, filter: filter, size: limit, return_result: false) do |entry|
         puts "DN: #{entry.dn}\t#{ldap_config.uid}: #{entry[ldap_config.uid]}"
       end