Remove un-truthy doc string.

Author: jvennix-r7

lib/msf/core/exploit/remote/browser_exploit_server.rb

@@ -567,7 +567,6 @@ def get_payload(cli, browser_info)
     end
 
     # @return [String] custom Javascript to check if a vulnerability is present
-    # @return [nil] when no such test is specified by the module
     def js_vuln_test
       all_reqs = self.module_info['BrowserRequirements'] || {}
       if all_reqs[:vuln_test].present?