botocore: add some more content to the README

This is taken from __init__.py documentation.

Author: xrmx

instrumentation/opentelemetry-instrumentation-botocore/README.rst

@@ -8,6 +8,40 @@ OpenTelemetry Botocore Tracing
 
 This library allows tracing requests made by the Botocore library.
 
+Extensions
+----------
+
+The instrumentation supports creating extensions for AWS services for enriching what is collected. We have extensions
+for the following AWS services:
+
+- Bedrock Runtime
+- DynamoDB
+- Lambda
+- SNS
+- SQS
+
+Bedrock Runtime
+***************
+
+This extension implements the GenAI semantic conventions for the following API calls:
+
+- Converse
+- ConverseStream
+- InvokeModel
+- InvokeModelWithResponseStream
+
+For the Converse and ConverseStream APIs tracing, events and metrics are implemented.
+
+For the InvokeModel and InvokeModelWithResponseStream APIs tracing, events and metrics implemented only for a subset of
+the available models, namely:
+- Amazon Titan models
+- Amazon Nova models
+- Anthropic Claude
+
+Tool calls with InvokeModel and InvokeModelWithResponseStream APIs are supported with:
+- Amazon Nova models
+- Anthropic Claude 3+
+
 Installation
 ------------