No issue: fix README link to file security issues.

README.md

@@ -71,3 +71,5 @@ git push <remote> --no-verify
     This Source Code Form is subject to the terms of the Mozilla Public
     License, v. 2.0. If a copy of the MPL was not distributed with this
     file, You can obtain one at http://mozilla.org/MPL/2.0/
+
+[sec issue]: https://bugzilla.mozilla.org/enter_bug.cgi?assigned_to=nobody%40mozilla.org&bug_ignored=0&bug_severity=normal&bug_status=NEW&cf_fx_iteration=---&cf_fx_points=---&component=Security%3A%20Android&contenttypemethod=list&contenttypeselection=text%2Fplain&defined_groups=1&flag_type-4=X&flag_type-607=X&flag_type-791=X&flag_type-800=X&flag_type-803=X&flag_type-936=X&flag_type-937=X&form_name=enter_bug&groups=mobile-core-security&maketemplate=Remember%20values%20as%20bookmarkable%20template&op_sys=Unspecified&priority=--&product=Fenix&rep_platform=Unspecified&target_milestone=---&version=unspecified