Fix issue template

The relative link doesn't work from the editor preview when creating a
new issue.
And the security link pointed at nothing.

ISSUE_TEMPLATE.md

@@ -1,4 +1,4 @@
-Do not report security issues in this bug tracker. Instead, contact [email protected] directly - see https://syncthing.net/security.html for more information.
+Do not report security issues in this bug tracker. Instead, contact [email protected] directly - see https://syncthing.net/security for more information.
 
 If your issue is a support request ("How do I get my devices to connect?" or similar), please use the support forum at https://forum.syncthing.net/ where a large number of helpful people hang out. This issue tracker is for reporting bugs or feature requests directly to the developers.
 
@@ -12,7 +12,7 @@ Also fill out the version information below and add log output or screenshots as
 
 Do not file a feature request unless you want to implement it yourself. This is
 due to the maintenance status of this project, see [the readme for
-context](./README.md#status-maintenance-mode---co-maintainers-welcome).
+context](https://github.com/syncthing/syncthing-android#status-maintenance-mode---co-maintainers-welcome).
 
 ### Version Information