github: update the new doc issue template to redirect the user to the new location

Signed-off-by: Hofi <[email protected]>

Author: HofiOne

.github/ISSUE_TEMPLATE/20-documentation-issue.md

@@ -1,20 +1,10 @@
 ---
 name: Documentation issue
-about: Use this template for reporting an issue in the documentation.
+about: Please use <a href="https://github.com/syslog-ng/syslog-ng.github.io/issues/new/choose">https://github.com/syslog-ng/syslog-ng.github.io/issues/new/choose</a>.
 title: ''
 labels: 'doc-bug'
 assignees: ''
 
 ---
 
-## Documentation version
-<!-- In which version of syslog-ng's documentation did you see the issue? -->
-
-## Incorrect section
-<!-- Which section of the documentation is wrong? Please include a link to it, if that is possible. -->
-
-## Description of the problem
-<!-- Which statements of the documentation are inaccurate? -->
-
-## Proposed solution
-<!-- What do you think the correction should be? -->
+Documentation issues are now handled in the new Documentation Center issue tracker. Please <a href="https://github.com/syslog-ng/syslog-ng.github.io/issues/new/choose">use that</a> instead.