added templates for release and bug

.gitlab/issue_templates/bug.md

+<!-- Use this template for a bug in MLAir. -->
+
+# Bug
+
+## Error description
+<!-- Provide a context when the bug / error arises -->
+
+## Error message
+<!-- Provide the error log if available -->
+
+## First guess on error origin
+<!-- Add first ideas where the error could come from -->
+
+## Error origin
+<!-- Fill this up when the bug / error origin has been found -->
+
+## Solution
+<!-- Short description how to solve the error -->
+

.gitlab/issue_templates/release.md

+<!-- Use this template for a new release of MLAir. -->
+
+# Release
+<!-- add your release version here -->
+
+vX.Y.Z
+
+## checklist
+
+* [ ] Create Release Issue
+* [ ] Create merge request: branch `release_vX.Y.Z` into `master`
+* [ ] Merge `develop` into `release_vX.Y.Z`
+* [ ] Checkout `release_vX.Y.Z`
+* [ ] Adjust `changelog.md` (see template for changelog)
+* [ ] Update version number in `mlair/__ init__.py`
+* [ ] Create new dist file: `python3 setup.py sdist bdist_wheel`
+* [ ] Update file link `distribution file (current version)` in `README.md`
+* [ ] Update file link in `docs/_source/get-started.rst`
+* [ ] Commit + push
+* [ ] Merge `release_vX.Y.Z` into `master`
+* [ ] Create new tag with
+    * [ ] distribution file (.whl)
+    * [ ] link to Documentation
+    * [ ] Example Jupyter Notebook
+    * [ ] changelog
+
+
+## template for changelog
+<!-- use this structure for the changelog. Link all issue to at least one item. -->
+
+```
+## vX.Y.Z -  yyyy-mm-dd  - <release description>
+
+### general:
+* text
+### new features:
+* words (issue)
+### technical:
+*
+```
\ No newline at end of file