Add NOTES.txt to the gotenberg chart

Gotenberg has no Ingress, so the notes lead with the cluster-internal URL and
point out that the Service listens on 80 while the container listens on 3000
— the mismatch a consumer such as paperless-ngx has to get right — plus the
port-forward command for reaching it by hand.

Three findings from measuring the running chart went in as warnings:

- The chart passes no command-line flags, so Gotenberg's basic auth, OIDC,
  SSRF guards and request timeout cannot be enabled through values at all.
- Memory, not disk, is the first limit to hit: at the default limit a large
  document gets the container OOM-killed, the caller sees the connection
  dropped rather than an HTTP error, and the notes give the exact kubectl
  command that prints OOMKilled.
- Temp space is an emptyDir counted against ephemeral-storage, where running
  out looks different — the pod is evicted and replaced, not restarted.

Both limits are read back through the chart's own resources helper, so the
printed figures follow limitFactor and any override instead of being
hardcoded. Refs #43.

gotenberg/Chart.yaml

@@ -5,7 +5,7 @@ icon: https://gotenberg.dev/img/logo.png
 
 type: application
 
-version: 5.0.0+up8.36.0
+version: 5.1.0+up8.36.0
 appVersion: "8.36.0"
 
 maintainers: