Update docs to specify to use Resource APIs to work with Resource (open-telemetry#1686)

Author: lzchen

docs/examples/basic_tracer/resources.py

@@ -20,6 +20,7 @@
     SimpleSpanProcessor,
 )
 
+# Use Resource.create() instead of constructor directly
 resource = Resource.create({"service.name": "basic_service"})
 
 trace.set_tracer_provider(TracerProvider(resource=resource))

opentelemetry-sdk/src/opentelemetry/sdk/resources/__init__.py

@@ -23,11 +23,13 @@
     these attributes can be included in the Resource.*
 
 Resource objects are created with `Resource.create`, which accepts attributes
-(key-values). Resource attributes can also be passed at process invocation in
-the :envvar:`OTEL_RESOURCE_ATTRIBUTES` environment variable. You should
-register your resource with the  `opentelemetry.sdk.trace.TracerProvider` by
-passing them into their constructors. The `Resource` passed to a provider is
-available to the exporter, which can send on this information as it sees fit.
+(key-values). Resources should NOT be created via constructor, and working with
+`Resource` objects should only be done via the Resource API methods. Resource
+attributes can also be passed at process invocation in the
+:envvar:`OTEL_RESOURCE_ATTRIBUTES` environment variable. You should register
+your resource with the  `opentelemetry.sdk.trace.TracerProvider` by passing
+them into their constructors. The `Resource` passed to a provider is available
+to the exporter, which can send on this information as it sees fit.
 
 .. code-block:: python