Updates the issue template with more instructions

ISSUE_TEMPLATE.md

@@ -1,4 +1,6 @@
-<!-- To enable logging to a GitLens channel in the Output pane, set `"gitlens.advanced.output.level": "verbose"` -->
+<!--
+If you are encountering an issue that says `See output channel for more details`, please enable output channel logging by setting `"gitlens.outputLevel": "verbose"` in your settings.json. This will enable logging to the GitLens channel in the Output pane. Once enabled, please attempt to reproduce the issue (if possible) and attach the relevant log lines from the GitLens channel.
+-->
 
 - GitLens Version:
 - VSCode Version: