Add doc to proto file

Signed-off-by: thomas.ebner <[email protected]>

api/envoy/extensions/tracers/opentelemetry/samplers/v3/dynatrace_sampler.proto

@@ -19,15 +19,30 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 // [#extension: envoy.tracers.opentelemetry.samplers.dynatrace]
 // [#next-free-field: 6]
 message DynatraceSamplerConfig {
+  // The Dynatrace tenant which receives the spans.
+  // This is a 8-character string containing characters and digits.
   string tenant = 1;
 
+  // The id of the Dynatrace cluster which the spans are reported to.
   string cluster_id = 2;
 
+  // The HTTP URI to fetch the sampler configuration (root spans per minute). For example:
+  //
+  // .. code-block:: yaml
+  //
+  //    http_uri:
+  //      uri: <tenant>.dev.dynatracelabs.com/api/v2/otlp/v1/traces
+  //      cluster: dynatrace
+  //      timeout: 10s
+  //
   config.core.v3.HttpUri http_uri = 3;
 
+  // A valid access token to be authenticated to use the Dynatrace API
   string token = 4;
 
-  // Default number of root spans per minute allowed by the sampler.
-  // The value is used if the number can't be requested from the Dynatrace API.
+  // Default number of root spans per minute used if the value can't be requested from the Dynatrace API.
+  // A default value of 1000 is used if:
+  // - no value is specified in the configuration
+  // - the value is set to 0
   uint32 root_spans_per_minute = 5;
 }