fix/doc-urls (#10246) [ci skip]

* docs(links): no relative links to website pages

* docs(images): remove unused images

docs/release-notes/10-3-0/README.md

@@ -55,7 +55,7 @@ You can use those custom fields to properly display text with a right-to-left or
 
 ## Support
 
-You can find useful information in the [OpenProject help section](../../../) or you can post your questions in the [OpenProject Forum](https://community.openproject.org/projects/openproject/boards).
+You can find useful information in the [OpenProject help section](https://www.openproject.org/docs/) or you can post your questions in the [OpenProject Forum](https://community.openproject.org/projects/openproject/boards).
 
 ### Upgrading your installation to OpenProject 10.3.
 

docs/release-notes/11-3-0/README.md

@@ -213,7 +213,7 @@ We update hosted OpenProject environments (Enterprise cloud) automatically.
 
 ## Support
 
-You will find useful information in the OpenProject [Documentation](../../../) or you can post your questions in the [Forum](https://community.openproject.org/projects/openproject/boards).
+You will find useful information in the OpenProject [Documentation](https://www.openproject.org/docs/) or you can post your questions in the [Forum](https://community.openproject.org/projects/openproject/boards).
 
 ## Credits