chore: Remove markdown from issue descriptions (#995)

It turns out that Markdown is not rendered in 'about' descriptions

Author: claremacrae

.github/ISSUE_TEMPLATE/config.yml

@@ -2,7 +2,7 @@ blank_issues_enabled: false
 contact_links:
   - name: Suggest a new feature
     url: https://github.com/obsidian-tasks-group/obsidian-tasks/discussions/new?category=ideas
-    about: Request a new feature or improvement in the Tasks plugin.<br>Please [search existing ideas](https://github.com/obsidian-tasks-group/obsidian-tasks/discussions/categories/ideas) first, and up-vote, to avoid duplicates.
+    about: Request a new feature or improvement in the Tasks plugin. Please search existing Discussion Ideas first, and up-vote, to avoid duplicates.
   - name: Ask a question
     url: https://github.com/obsidian-tasks-group/obsidian-tasks/discussions/new?category=q-a
-    about: Ask for help with using the Tasks plugin.<br>In case your question has been asked before, for quicker results you can [search existing questions](https://github.com/obsidian-tasks-group/obsidian-tasks/discussions/categories/q-a).
+    about: Ask for help with using the Tasks plugin. In case your question has been asked before, for quicker results you can search existing Discussion Q&As.