Merge branch 'add_description_templates' into 'master'

[gitlab] add description templates

See merge request tomotools/tomwer!276

.gitlab/issue_templates/bug_report.md

+Description
+-----------
+
+(Summarize the bug encountered concisely)
+
+
+Steps to reproduce
+------------------
+
+(How one can reproduce the issue - this is very important)
+
+1. ...
+
+2. ...
+
+3. ...
+
+
+What is the current bug behavior?
+---------------------------------
+
+(What actually happens)
+
+
+
+What is the expected correct behavior?
+--------------------------------------
+
+(What you should see instead)
+
+
+Relevant logs, error output, screenshots ...
+--------------------------------------------
+
+(Paste any relevant logs - please use code blocks (```) to format console output,
+logs, and code as it's very hard to read otherwise.)
+
+
+Possible fixes
+--------------
+
+(If you can, link to the line of code that might be responsible for the problem)
+
+
+What versions of software are you using?
+----------------------------------------
+
+
+Any other comments?
+-------------------
+
+...

.gitlab/issue_templates/feature_request.md

+Description
+-----------
+
+
+User Case(s)
+------------
+
+
+Test Case(s)
+------------
+
+
+Raw material (example script, data...)
+--------------------------------------
+
+Any other comments?
+-------------------
+
+...

.gitlab/merge_request_templates/default_merge_request.md

+Description / Goal
+------------------
+
+TODO list
+---------
+
+- [ ] 
+...
+- [ ] doc
+- [ ] add test
+
+INFO (how to use...)
+--------------------
+
+Any warning ?
+-------------
+
+associated materials (screenshot, test scripts...)
+--------------------------------------------------