Label "Installed Versions" item in Issue template (#3832)

* Label Installed Versions details in GH Issue template

* Update bug_report.md

Author: max-sixty

.github/ISSUE_TEMPLATE/bug_report.md

@@ -25,8 +25,9 @@ assignees: ''
 <!-- this should explain why the current behavior is a problem and why the expected output is a better solution -->
 
 
-#### Output of ``xr.show_versions()``
-<details>
+#### Versions
+
+<details><summary>Output of `xr.show_versions()`</summary>
 <!-- Paste the output here xr.show_versions() here -->
 
 </details>