Start (naive) troubleshooting section in README (#156)

* Start (naive) troubleshooting section in README

* Add Log Explorer queries examples

* Are not

* Rephrase as instructions

Author: leplatrem

README.md

@@ -219,6 +219,60 @@ GET /whiteboard_tags/
 }
 ```
 
+## Troubleshooting
+
+### Bugzilla tickets are not showing up as issues on Jira
+
+As a consumer, you can:
+
+- Open https://jbi.services.mozilla.com/powered_by_jbi/ and check that your project is listed and enabled there
+- Open https://jbi.services.mozilla.com/__heartbeat__ and make sure everything is `true`
+
+If you have access to the configured Bugzilla account:
+
+- Open https://bugzilla.mozilla.org/userprefs.cgi?tab=webhooks
+- Check that Webhook is still **enabled**
+- Check that WebHook is setup to be executed for your product
+- (*if applies*) Check that account can read the private bugs
+
+### Log Explorer Queries Examples
+
+* All incoming WebHooks:
+
+```
+jsonPayload.Type="request.summary"
+jsonPayload.Fields.path="/bugzilla_webhook"
+```
+
+* All action log entries:
+
+```
+jsonPayload.Type!="request.summary" AND
+(
+   NOT jsonPayload.Fields.operation:*  --Entries without `operation` field
+   OR (jsonPayload.Fields.operation!="handle" AND jsonPayload.Fields.operation!="ignore")
+)
+```
+
+* For bugs whose whiteboard contains a certain string:
+
+```
+jsonPayload.Fields.bug.whiteboard=~"flowstate"
+```
+
+* For a certain Bug number:
+
+```
+jsonPayload.Fields.bug.id=1780798
+```
+
+* For a certain Jira project:
+
+```
+jsonPayload.Fields.action.parameters.jira_project_key="MR"
+```
+
+
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