Merge branch 'fix/issue-template' into 'master'

Simplifies the bug report gitlab template.

See merge request frama-c/frama-c!3121

.gitlab/issue_templates/bug_report.md

+<!--
 Thank you for submitting an issue to the Frama-C team.
 We propose the following template to ease the process.
 Please directly edit it inline to provide the required information.
 
-Before submitting the issue, please confirm (by adding a X in the [ ]):
+Before submitting the issue, please verify:
+- the issue has not yet been reported on [Gitlab](https://git.frama-c.com/pub/frama-c/issues);
+- you installed Frama-C as prescribed in the [instructions](INSTALL.md).
 
-- [ ] the issue has not yet been reported on [Gitlab](https://git.frama-c.com/pub/frama-c/issues);
-- [ ] the issue has not yet been reported on our old
-  [BTS](https://bts.frama-c.com) (*note: the old BTS is deprecated*);
-- [ ] you installed Frama-C as prescribed in the [instructions](INSTALL.md).
+If the issue applies to a specific Frama-C plug-in, please prefix the title
+by the plug-in name: [Eva], [WP], [E-ACSL]…
+-->
 
-# Contextual information
+### Steps to reproduce the issue
 
-- Frama-C installation mode: *Opam, Homebrew, package from distribution, from source, ...*
-- Frama-C version: *Frama-C version* (as reported by `frama-c -version`)
-- Plug-in used: *Plug-in used*
-- OS name: *OS name*
-- OS version: *OS version*
-
-*Please add specific information deemed relevant with regard to this issue.*
+<!--
+Please indicate here steps to follow to get a [minimal, complete, and verifiable example](https://stackoverflow.com/help/mcve) which reproduces the issue.
+-->
 
-# Steps to reproduce the issue
+### Expected behaviour
 
-*Please indicate here steps to follow to get a [minimal, complete, and verifiable example](https://stackoverflow.com/help/mcve) which reproduces the issue.*
+<!--
+Please explain here what is the expected behaviour.
+-->
 
-# Expected behaviour
+### Actual behaviour
 
-*Please explain here what is the expected behaviour.*
+<!--
+Please explain here what is the actual (faulty) behaviour.
+-->
 
-# Actual behaviour
+### Contextual information
 
-*Please explain here what is the actual (faulty) behaviour.*
+- Frama-C installation mode: *Opam, Homebrew, package from distribution, from source, ...*
+- Frama-C version: *Frama-C version* (as reported by `frama-c -version`)
+- Plug-in used: *Plug-in used*
+- OS name: *OS name*
+- OS version: *OS version*
 
-# Fix ideas
+### Additional information (optional)
 
-*Please tell us if you already tried some work-arounds or have some ideas to solve this issue.*
+<!--
+You may add here any information deemed relevant with regard to this issue,
+and tell us if you already tried some workarounds or have some ideas to solve this issue.
+-->