Update troubleshooting (#498)

* Update troubleshooting

- remove "no label" title
- add tracing part

Signed-off-by: Xiang Dai <764524258@qq.com>

* Add helm help

Signed-off-by: Xiang Dai <764524258@qq.com>

docs/troubleshooting.md

@@ -45,8 +45,6 @@ to
 
 Both binaries support a log level parameter on the command-line, e.g.: `loki —log.level= debug ...`
 
-## No labels:
-
 ## Failed to create target, "ioutil.ReadDir: readdirent: not a directory"
 
 The promtail configuration contains a `__path__` entry to a directory that promtail cannot find.
@@ -82,3 +80,13 @@ Once connected, verify the config in `/etc/promtail/promtail.yml` is what you ex
 Also check `/var/log/positions.yaml` and make sure promtail is tailing the logs you would expect
 
 You can check the promtail log by looking in `/var/log/containers` at the promtail container log
+
+## Enable tracing for loki
+
+We support (jaeger)[https://www.jaegertracing.io/] to trace loki, just add env `JAEGER_AGENT_HOST` to where loki run, and you can use jaeger to trace.
+
+If you deploy with helm, refer to following command:
+
+```bash
+$ helm upgrade --install loki loki/loki --set "loki.jaegerAgentHost=YOUR_JAEGER_AGENT_HOST"
+```