docs: Add nginx_ingress_controller.access integration

[rogercoll]

This PR contains a sample configuration for the OpenTelemetry collector to parse and forward Nginx Ingress Controller Access logs. A Kibana dashboard is also provided.

Decisions changelog

• A custom datastream.dataset attribute (nginx_ingress_controller.access) has been set, the reasoning behind it is to have a different datastream for each receiver/integration.
• ExtractGrockPattern has been used instead of regex, the configuration became less error prone and easier to align with Elastic's current pipeline: https://github.com/elastic/integrations/blob/main/packages/nginx_ingress_controller/data_stream/access/elasticsearch/ingest_pipeline/default.yml
• Every known log field has been extracted and added as a log attribute, this should be revised once the Nginx Ingress Controller Log record becomes an OpenTelemetry Event: https://github.com/open-telemetry/semantic-conventions/pull/982
• Even some attributes are not yet defined in SemConv, an approximate structure has been used (e.g http.request.id). Otel structure in favor of ECS.
• The GeoIP processor is disabled as it requires a local database, uncomment its configuration with a valid database path if needed.
• The sample configuration uses resourcedetection/system processor to retrieve and add the host.name attribute, which can be used for filtering in the dashboard.

Missing charts

• Operating System breakdown (No OS UserAgent attributes with OTTL)
• Upstream response time: A Nginx Ingress Controller response can come from multiple servers, the final upstream.response.time is computed by the sum of all the responses. All the responses are captured in an array attribute, but there is no OTTL function to sum all the values (e.g upstream.response.time: Slice(["0.002", "0.001"])). See Elastic integration https://github.com/elastic/integrations/blob/main/packages/nginx_ingress_controller/data_stream/access/elasticsearch/ingest_pipeline/default.yml#L111

[rogercoll]

Closing in favor of https://github.com/elastic/integrations/pull/11285