Add document wrt hackathon

doc.zih.tu-dresden.de/hackathon.md

+# Hackathon June 2021
+
+The goals for the hackathon are:
+
+* Familiarize main editors (ZIH admin group and domain experts) with new workflow and system
+* Bringing new compendium to life by
+  * Reviewing content of old compendium
+  * Transferring reviewed content into new structure and system
+
+## twiki2md
+
+The script `twiki2md` converts twiki source files into markdown source files using pandoc. It outputs the
+markdown source files according to (old) pages tree. The output can be found at branch `preview`
+within directory `compendium/`.
+
+## Steps
+
+### Familiarize with New Wiki System
+
+
+### Transferring Content
+
+1. Grab a markdown source file from `compendium` directory (a topic you are comfortable with)
+1. Review the markdown source file
+  * Replace or remove (leftover) html constructs in markdown source file
+  * Add ticks for code blocks and command if necessary
+  * Fix internal links (mark as todo if necessary)
+  * Review and update, remove outdated content
+1. Find place in new structure according to
+[Typical Project Schedule](https://doc.zih.tu-dresden.de/hpc-wiki/bin/view/Compendium/TypicalProjectSchedule)
+  * Copy reviewed markdown source file to `doc.zih.tu-dresden.de/docs/SUBDIR/<FILENAME>.md`
+  * Update navigation section in `mkdocs.yaml`
+1. Apply git workflow
+  * Add `<FILENAME>.md` to git repository
+  * Commit all changed file, e.g., `<FILENAME.md>`, `mkdocs.yaml` and graphics from this documentation
+      page
+  * Push changes to new branch
+    * ``git push origin 
+  * Create [merge request](https://gitlab.hrz.tu-chemnitz.de/zih/hpc-compendium/hpc-compendium/-/merge_requests)