Adds infos about vulnerability disclosures (#4413)

* Create SECURITY.md

* Update SECURITY.md

* Update SECURITY.md

* Update ISSUE_TEMPLATE.md

* Update ISSUE_TEMPLATE.md

* Clarify time table from contact to fix

* change times to days

.github/ISSUE_TEMPLATE.md

@@ -4,6 +4,8 @@ If you have a non-bug question, ask on Stack Overflow or Server Fault:
 - https://stackoverflow.com/questions/tagged/parse.com 
 - https://serverfault.com/tags/parse
 
+If you have a vulnerability disclosure, please follow our policy available here https://github.com/parse-community/parse-server/blob/master/SECURITY.md
+
 You may also search through existing issues before opening a new one: https://github.com/parse-community/parse-server/issues?utf8=%E2%9C%93&q=is%3Aissue 
 
 --- Please use this template. If you don't use this template, your issue may be closed without comment. ---