👔 Move GitHub templates, update README (#24199)

.github/ISSUE_TEMPLATE/config.yml

@@ -1,7 +1,7 @@
 blank_issues_enabled: false
 contact_links:
   - name: 📖 Marlin Documentation
-    url: http://marlinfw.org/
+    url: https://marlinfw.org/
     about: Lots of documentation on installing and using Marlin.
   - name: 👤 MarlinFirmware Facebook group
     url: https://www.facebook.com/groups/1049718498464482
@@ -10,7 +10,7 @@ contact_links:
     url: https://discord.gg/n5NJ59y
     about: Join the Discord server for support and discussion.
   - name: 🔗 Marlin Discussion Forum
-    url: http://forums.reprap.org/list.php?415
+    url: https://reprap.org/forum/list.php?415
     about: A searchable web forum hosted by RepRap dot org.
   - name: 📺 Marlin Videos on YouTube
     url: https://www.youtube.com/results?search_query=marlin+firmware