feat(telemetry): add error section in custom attributes configuration

[bnjjj]

close #1434

Add the ability to add custom attributes on errors:

telemetry:
  metrics:
    prometheus:
      enabled: true
    common:
      attributes:
        subgraph:
          all:
            errors: # Only works if it's a valid GraphQL error
              include_messages: true # Will include the error message in a message attribute
              extensions: # Include extension data
                - name: subgraph_error_extended_type # Name of the attribute
                  path: .type # JSON query path to fetch data from extensions

[BrynCooke]

Great!
Only thing would be to add a bit more in the docs about what you can expect in terms of output by using this feature.

[garypen]

Looks good, one small change please.