issue_templates/Bug: be more descriptive

.gitlab/issue_templates/Bug.md

@@ -1,16 +1,40 @@
-#### SNM Version: (e.g. v2.1.3)
+## Issue description
-#### Nixos Version: (e.g. 18.03 or unstable)
 
-#### Relevant part of the config to reproduce:
+### What I expected to happen:
 
+### What happened:
 
+## Technical details
 
-#### What I expected to happen:
+<!--
+If possible, please run `nix-shell -p nix-info --run "nix-info -m"` on the mail
+server and paste the results in a fenced code block:
+https://about.gitlab.com/handbook/product/technical-writing/markdown-guide/#code-blocks
 
+Otherwise, please specify the NixOS version (e.g. 18.03 or unstable) that the
+mail server is running on.
+-->
 
+### SNM Version
 
-#### What happened:
+<!--
+For example, `v2.1.3` or the output of `git log -1` if you're using a git submodule.
+-->
 
+### Relevant part of the config to reproduce:
+<!--
+If applicable, please paste your `mailserver` config here and redact any
+sensitive details such as `hashedPassword`.
+-->
 
+### Relevant `journald` log:
 
-#### Relevant journald log:
+<!--
+For example, if you're having a problem with Dovecot, first identity the Dovecot
+service name by examining the output of `systemctl list-unit-files`.  Notice
+that it is `dovecot2.service`, so paste here relevant lines from the output of
+`journalctl -u dovecot2 --since="today" | less`.
+
+If you don't know what particular unit is causing the problem, you can search
+for details in the output of `journalctl --since="today" | less`.
+-->