docs(otel): add sampling example and fix config key casing

Signed-off-by: Adrian Cole <[email protected]>

Author: codefromthecrypt

documentation/docs/guides/config-files.md

@@ -99,8 +99,8 @@ GOOSE_SEARCH_PATHS:
 # Observability (OpenTelemetry)
 # Prefer ENV, which overrides this configuration and fully supports 
 # OTel semantics. See the environment-variables guide for details.
-OTEL_EXPORTER_OTLP_ENDPOINT: "http://localhost:4318"
-OTEL_EXPORTER_OTLP_TIMEOUT: 20000
+otel_exporter_otlp_endpoint: "http://localhost:4318"
+otel_exporter_otlp_timeout: 20000
 
 # Security Configuration
 SECURITY_PROMPT_ENABLED: true

documentation/docs/guides/environment-variables.md

@@ -479,6 +479,10 @@ export OTEL_EXPORTER_OTLP_ENDPOINT="http://localhost:4318"
 
 # Debug traces to console (no collector needed)
 export OTEL_TRACES_EXPORTER="console"
+
+# Sample 10% of traces (reduce volume in production)
+export OTEL_TRACES_SAMPLER="parentbased_traceidratio"
+export OTEL_TRACES_SAMPLER_ARG="0.1"
 ```
 
 [otel-env]: https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/