[gimp-web] devel-docs: add a "Debugging mirror issues" subsection.

[Jehan <jehanp src gnome org>]

commit 373babc44248ca5731da3f059cec4aa8dba50e90
Author: Jehan <jehan girinstud io>
Date:   Tue Aug 30 23:03:21 2022 +0200

    devel-docs: add a "Debugging mirror issues" subsection.
    
    I need to keep track how to get the debug logs as the OpenShift web GUI
    is a real mystery to me!

 devel-docs/mirror-howto.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)
---
diff --git a/devel-docs/mirror-howto.md b/devel-docs/mirror-howto.md
index e50ab0bd..9310c4b8 100644
--- a/devel-docs/mirror-howto.md
+++ b/devel-docs/mirror-howto.md
@@ -176,6 +176,19 @@ Of course, the public website will be updated when you merge `testing`
 into `master` branch which does not have to happen immediately.
 
 ## Mirror maintenance
+### Debugging mirror issues
+
+Sometimes the `mb logs` command might not give very detailed
+information, but OpenShift contains much more detailed logs:
+
+* Go to https://console-openshift-console.apps.openshift4.gnome.org/
+* Go to "Administrator" view.
+* Click Workloads → Pods
+* Filter for mirrorbits
+* Select one of the running pods (not the `redis-*` or the `*-deploy`
+  pods).
+* Click the `Logs` tab.
+
 ### Conf files must match
 
 Make sure that `auth users` in `[gimp]` section of `/etc/rsyncd.conf`