add question about reverse proxy

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

.github/ISSUE_TEMPLATE/bug_report.md

@@ -32,6 +32,8 @@ Nextcloud app version:
 
 Nextcloud server version:
 
+Reverse proxy:
+
 ### Logs
 #### Web server error log
 ```