[chore] Mark otel.* attributes as stable in yaml (open-telemetry#784)

Author: Liudmila Molkova

model/scope/exporter/exporter.yaml

@@ -8,10 +8,12 @@ groups:
         type: string
         brief: The name of the instrumentation scope - (`InstrumentationScope.Name` in OTLP).
         examples: ['io.opentelemetry.contrib.mongodb']
+        stability: stable
       - id: version
         type: string
         brief: The version of the instrumentation scope - (`InstrumentationScope.Version` in OTLP).
         examples: ['1.0.0']
+        stability: stable
   - id: otel.library
     prefix: otel.library
     type: resource

model/trace/exporter/exporter.yaml

@@ -15,7 +15,9 @@ groups:
               value: ERROR
               brief: 'The operation contains an error.'
         brief: Name of the code, either "OK" or "ERROR". MUST NOT be set if the status code is UNSET.
+        stability: stable
       - id: status_description
         type: string
         brief: "Description of the Status if it has a value, otherwise not set."
         examples: ['resource not found']
+        stability: stable