tetragon: docs, minor updates to metrics concepts

Update Metrics section to clarrify PACKAGE is about
local installs. I at least was confused.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>

docs/content/en/docs/concepts/metrics.md

@@ -42,9 +42,10 @@ To forward the metrics port locally, use `kubectl port forward`:
 kubectl -n kube-system port-forward service/tetragon 2112:2112
 ```
 
-## Package
+## Systemd and Local Packages
 
-By default, metrics are disabled, which can be enabled using `--metrics-server`
+By default, metrics are disabled when following systemd installation or
+using release images to install locally. The metrics can be enabled using `--metrics-server`
 flag, by specifying the address.
 
 Alternatively, the [examples/configuration/tetragon.yaml](https://github.com/cilium/tetragon/blob/main/examples/configuration/tetragon.yaml)