Update documentation-task.md

.gitlab/issue_templates/documentation-task.md

-## Task todo
+# Describe what is needed
 
+1. Update issue topic according description
+2. ..
+3. ..
 
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-- [ ] First
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+# Responsible
 
+* name/stakeholder
 
-/label ~Documentation
\ No newline at end of file
+# Links & Sources
+
+/label ~Documentation
+/label ~Backlog
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