Update Sample otelcol config (#4397)

* update to valid otlp receiver config

With recent versions of OpenTelemetry Collector it is necessary to specify protocols

* simplify exporter configuration and note advanced option

* fix link syntax

* Update docs/en/observability/apm/collect-application-data/open-telemetry/otel-direct.asciidoc

Co-authored-by: Arianna Laudazzi <[email protected]>

---------

Co-authored-by: Arianna Laudazzi <[email protected]>
(cherry picked from commit 2ba3a80)

docs/en/observability/apm/collect-application-data/open-telemetry/otel-direct.asciidoc

@@ -26,7 +26,11 @@ Connect your OpenTelemetry Collector instances to Elastic {observability} using
 receivers: <1>
   # ...
   otlp:
-
+    protocols:
+      grpc:
+        endpoint: 0.0.0.0:4317
+      http:
+        endpoint: 0.0.0.0:4318
 processors: <2>
   # ...
   memory_limiter:
@@ -37,7 +41,7 @@ processors: <2>
 exporters:
   debug:
     verbosity: detailed <3>
-  otlp/elastic: <4>
+  otlp: <4>
     # Elastic APM server https endpoint without the "https://" prefix
     endpoint: "${env:ELASTIC_APM_SERVER_ENDPOINT}" <5> <7>
     headers:
@@ -49,15 +53,15 @@ service:
     traces:
       receivers: [otlp]
       processors: [..., memory_limiter, batch]
-      exporters: [debug, otlp/elastic]
+      exporters: [debug, otlp]
     metrics:
       receivers: [otlp]
       processors: [..., memory_limiter, batch]
-      exporters: [debug, otlp/elastic]
+      exporters: [debug, otlp]
     logs: <8>
       receivers: [otlp]
       processors: [..., memory_limiter, batch]
-      exporters: [debug, otlp/elastic]
+      exporters: [debug, otlp]
 ----
 <1> The receivers, like the
 https://github.com/open-telemetry/opentelemetry-collector/tree/main/receiver/otlpreceiver[OTLP receiver], that forward data emitted by APM agents, or the https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/receiver/hostmetricsreceiver[host metrics receiver].
@@ -69,6 +73,7 @@ and the OTLP protocol over HTTP transport https://opentelemetry.io/docs/specs/ot
 To learn more about these exporters, see the OpenTelemetry Collector documentation:
 https://github.com/open-telemetry/opentelemetry-collector/tree/main/exporter/otlphttpexporter[OTLP/HTTP Exporter] or
 https://github.com/open-telemetry/opentelemetry-collector/tree/main/exporter/otlpexporter[OTLP/gRPC exporter].
+When adding an endpoint to an existing configuration an optional name component can be added, like `otlp/elastic`, to distinguish endpoints as described in the https://opentelemetry.io/docs/collector/configuration/#basics[OpenTelemetry Collector Configuration Basics].
 <5> Hostname and port of the APM Server endpoint. For example, `elastic-apm-server:8200`.
 <6> Credential for Elastic APM <<apm-secret-token,secret token authorization>> (`Authorization: "Bearer a_secret_token"`) or <<apm-api-key,API key authorization>> (`Authorization: "ApiKey an_api_key"`).
 <7> Environment-specific configuration parameters can be conveniently passed in as environment variables documented https://opentelemetry.io/docs/collector/configuration/#environment-variables[here] (e.g. `ELASTIC_APM_SERVER_ENDPOINT` and `ELASTIC_APM_SECRET_TOKEN`).