Move contact info to a separate page and add a security contact

Someone asked about it on IRC, this documents it somewhat.
This being tied to me alone isn't ideal, but better than nothing I guess.

Author: lazka

Diff for: mkdocs.yml

@@ -92,3 +92,4 @@ nav:
         - wiki/Sudo.md
         - wiki/Terminals.md
         - wiki/JIT-Debugging.md
+    - 'contact.md'

Diff for: web/contact.md

@@ -0,0 +1,23 @@
+# Support & Contact
+
+*   read our [wiki](https://www.msys2.org/wiki/Home/)
+*   browse our [package lists](https://packages.msys2.org/)
+*   search for and file [issues for msys2 packages on GitHub](https://github.com/msys2/msys2-packages/issues)
+*   search for and file [issues for mingw-w64 packages on GitHub](https://github.com/msys2/mingw-packages/issues)
+*   search for very old [tickets on SourceForge](https://sourceforge.net/p/msys2/tickets/)
+*   read and post to our [mailing list](https://sourceforge.net/p/msys2/mailman/msys2-users/)
+*   talk in our [Gitter room](https://gitter.im/msys2/msys2)
+*   talk in our [Discord server](https://discord.gg/jPQdRdDcT9)
+*   talk in our [IRC channel](irc://irc.oftc.net:6667/msys2)
+*   follow our [Twitter account](https://twitter.com/msys2org)
+*   read older [discussion on SourceForge](https://sourceforge.net/p/msys2/discussion/general/)
+*   more links on our [homepage on GitHub](https://github.com/msys2/msys2)
+
+## Security Contact
+
+For reporting vulnerabilities, managing coordinated security updates, or anything which shouldn't be posted to the public GitHub issue tracker:
+
+* Contact: reiter.christoph@gmail.com
+* PGP key for encryption, if needed: https://keyserver.ubuntu.com/pks/lookup?op=vindex&search=0x46BD761F7A49B0EC&fingerprint=on
+
+If there is no timely response please ping us on the other support channels.

Diff for: web/index.md

@@ -187,23 +187,6 @@ Our main server is sponsored by [appfleet.com](https://appfleet.com)
 * [Renato Silva](https://github.com/renatosilva)
 * [niXman](https://github.com/niXman)
 
-
-## Support and Contact
-
-*   read our [wiki](https://www.msys2.org/wiki/Home/)
-*   browse our [package lists](https://packages.msys2.org/)
-*   search for and file [issues for msys2 packages on GitHub](https://github.com/msys2/msys2-packages/issues)
-*   search for and file [issues for mingw-w64 packages on GitHub](https://github.com/msys2/mingw-packages/issues)
-*   search for very old [tickets on SourceForge](https://sourceforge.net/p/msys2/tickets/)
-*   read and post to our [mailing list](https://sourceforge.net/p/msys2/mailman/msys2-users/)
-*   talk in our [Gitter room](https://gitter.im/msys2/msys2)
-*   talk in our [Discord server](https://discord.gg/jPQdRdDcT9)
-*   talk in our [IRC channel](irc://irc.oftc.net:6667/msys2)
-*   follow our [Twitter account](https://twitter.com/msys2org)
-*   read older [discussion on SourceForge](https://sourceforge.net/p/msys2/discussion/general/)
-*   more links on our [homepage on GitHub](https://github.com/msys2/msys2)
-
-
 ## Donations
 
 #### Alexey Pavlov ([@alexpux](https://github.com/alexpux))