Update templates

.gitlab/issue_templates/Bug report.md

@@ -1,3 +1,5 @@
+<!-- Put a brief summary of the issue in the title. -->
+
 # My system
 
 - Distribution (name and version):

.gitlab/issue_templates/Feature request.md

@@ -1,3 +1,5 @@
+<!-- Put a brief summary of the feature in the title, don't start it with "[Feature request]". -->
+
 <!-- Describe as precisely as possible the feature you want to be added: how should it work? What does it do? -->
 
 

.gitlab/issue_templates/Suggestion.md

@@ -1,3 +1,4 @@
+<!-- This is for general discussion on the extension. For specific issues (bug report, theme request, feature request), please use the appropriate template. -->
 
 
 <!-- Don't remove this line -->

.gitlab/issue_templates/Theme request.md

@@ -1,3 +1,5 @@
+<!-- Put the name of the theme in the title, don't start it with "[Theme request]". -->
+
 - Theme name:
 - Theme repository or download link: