Maintenance.md

+# Maintenance
+
+There are several tasks that need to be done regularly.
+
+## Link Checker
+
+Thanks to the Rechenzentrum, all projects that are properly registered feature a link checker, that runs once a month and checks for dead links:
+
+https://github.com/linkchecker/linkchecker
+
+Apparently this job checks all folders on `www3` and `www3-dev` recursively and generates an issue if some links appear to be broken:
+
+![image](uploads/944cb06faac81be2c693e2fc3469034d/image.png)
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