Updating README instructions

[z0r1k]

What kind of change does this PR introduce?

This is docs update.

What is the current behavior?

Config like this

  - job_name: supabase-foobarbaz-us-east-1-abcdef
    scheme: https
    metrics_path: "/customer/v1/privileged/metrics"
    basic_auth:
      username: service_role
      password: __SUPABASE_SERVICE_ROLE_KEY__
    static_configs:
      - targets: ["foobarbaz-us-east-1-abcdef.supabase.co"]
        labels:
          - supabase_project_ref: "foobarbaz-us-east-1-abcdef"

causes an issue:

"ts=2025-04-02T14:20:12.963Z caller=main.go:512 level=error msg="Error loading config (--config.file=/etc/prometheus/prometheus.yml)" file=/etc/prometheus/prometheus.yml err="parsing YAML file /etc/prometheus/prometheus.yml: yaml: unmarshal errors:\n  line 27: cannot unmarshal !!seq into model.LabelSet\n  line 40: cannot unmarshal !!seq into model.LabelSet""

What is the new behavior?

No more error.

[z0r1k]

It seems like this actually could be a duplicate of #40 but current PR has no merge conflicts.

[encima]

Good catch, I did not see the other PR either so my bad (the same bad that made me do the initial typo...)

Still waiting on backend but maybe the codeowners should change