Fix header level in README.md (open-telemetry#684)

Co-authored-by: Armin Ruech <7052238+arminru@users.noreply.github.com>

docs/resource/README.md

@@ -20,7 +20,7 @@ This document defines standard attributes for resources. These attributes are ty
 - [Document Conventions](#document-conventions)
 - [Attributes with Special Handling](#attributes-with-special-handling)
   * [Semantic Attributes with Dedicated Environment Variable](#semantic-attributes-with-dedicated-environment-variable)
-- [Semantic Attributes with SDK-provided Default Value](#semantic-attributes-with-sdk-provided-default-value)
+  * [Semantic Attributes with SDK-provided Default Value](#semantic-attributes-with-sdk-provided-default-value)
 - [Service](#service)
 - [Service (Experimental)](#service-experimental)
 - [Telemetry SDK](#telemetry-sdk)
@@ -63,7 +63,7 @@ as specified in [OpenTelemetry Environment Variable Specification](https://githu
 
 - [`service.name`](#service)
 
-## Semantic Attributes with SDK-provided Default Value
+### Semantic Attributes with SDK-provided Default Value
 
 These are the attributes which MUST be provided by the SDK
 as specified in the [Resource SDK specification](https://github.com/open-telemetry/opentelemetry-specification/tree/v1.26.0/specification/resource/sdk.md#sdk-provided-resource-attributes):