Fix outdated Security Disclosure Policy references (#17341)

.github/ISSUE_TEMPLATE.md

@@ -2,4 +2,4 @@
 (using a matrix.org account if necessary). We do not use GitHub issues for
 support.
 
-**If you want to report a security issue** please see https://matrix.org/security-disclosure-policy/
+**If you want to report a security issue** please see https://element.io/security/security-disclosure-policy

.github/ISSUE_TEMPLATE/BUG_REPORT.yml

@@ -7,7 +7,7 @@ body:
         **THIS IS NOT A SUPPORT CHANNEL!**
         **IF YOU HAVE SUPPORT QUESTIONS ABOUT RUNNING OR CONFIGURING YOUR OWN HOME SERVER**, please ask in **[#synapse:matrix.org](https://matrix.to/#/#synapse:matrix.org)** (using a matrix.org account if necessary).
 
-        If you want to report a security issue, please see https://matrix.org/security-disclosure-policy/
+        If you want to report a security issue, please see https://element.io/security/security-disclosure-policy
 
         This is a bug report form. By following the instructions below and completing the sections with your information, you will help the us to get all the necessary data to fix your issue.
 

changelog.d/17341.doc

@@ -0,0 +1 @@
+Fix stale references to the Foundation's Security Disclosure Policy.

docs/welcome_and_overview.md

@@ -62,6 +62,6 @@ following documentation:
 
 ## Reporting a security vulnerability
 
-If you've found a security issue in Synapse or any other Matrix.org Foundation
-project, please report it to us in accordance with our [Security Disclosure
-Policy](https://www.matrix.org/security-disclosure-policy/). Thank you!
+If you've found a security issue in Synapse or any other Element project,
+please report it to us in accordance with our [Security Disclosure
+Policy](https://element.io/security/security-disclosure-policy). Thank you!