(gitlab) Rewording of some of the gitlab templates

Merge request templates were suitable only for bug fixes. The changes
in this commit includes a few lines for (new) features too.

Src-commit: 41c178606e88c788ebbb68431b58710c644f75f9

Author: jfmc

.gitlab/issue_templates/Bug.md

@@ -1,17 +1,17 @@
-## Bug Summary
+## Bug description
 
-(Summarize the bug encountered concisely)
+Describe the bug concisely.
 
 ## Steps to reproduce
 
-(How to reproduce the issue)
+How to reproduce it.
 
-## What is the current bug behavior?
+## Current vs expected behavior
 
-(What actually happens)
+What actually happens and what should happen instead.
 
-## What is the expected correct behavior?
+## Hints for a fix
 
-(What should happen instead)
+If known, add here any hints to fix it.
 
 /label ~Bug

.gitlab/issue_templates/Feature.md

@@ -1,9 +1,9 @@
-## Feature Summary
+## Feature description
 
-(Summarize the new feature concisely)
+Describe the new feature concisely (if possible with examples).
 
-## Why do we want it?
+## Benefits
 
-(How is this feature useful?)
+For whom and why.
 
 /label ~NewFeature

.gitlab/merge_request_templates/Template.md

@@ -1,15 +1,24 @@
-(_Relevant module name_) _Commit message_
-
-**Copy issue description without labels**
+(_component_) _One-line description_
 
 ## Summary
 
-_Explain your solution, changes w.r.t. previous code and mention any
-noteworthy aspect of this MR_
+Description and motivation of this MR here. If there exist, you may
+reuse text from the issue overview here.
+
+For **bug fixes**, this text this should answer (directly or indirectly):
+ - What was broken? (use examples)
+ - Wht is the expected behavior? (use examples)
+ - How is it fixed? (overview of the fix)
+ - (if applicable) Are there alternative (better) fixes? (which for
+   some reason we do not implement here)
+
+For **new features**, this text should answer:
+ - What this new feature adds?
+ - What are the benefits (for whom and why)?
 
-## Why is it the best solution now?
+## Detailed description
 
-_(Only if not explained above) Explain why your solution is
-implemented this way._
+If it not trivial, describe which files, modules, predicates, etc. has
+been added/changed.
 
 Closes #_Issue number_