docs: add newly created Slack Channel

Author: heitorlessa

README.md

@@ -7,6 +7,8 @@ A suite of utilities for AWS Lambda functions that makes tracing with AWS X-Ray,
 
 **[📜Documentation](https://awslabs.github.io/aws-lambda-powertools-python/)** | **[API Docs](https://awslabs.github.io/aws-lambda-powertools-python/api/)** | **[🐍PyPi](https://pypi.org/project/aws-lambda-powertools/)** | **[Feature request](https://github.com/awslabs/aws-lambda-powertools-python/issues/new?assignees=&labels=feature-request%2C+triage&template=feature_request.md&title=)** | **[🐛Bug Report](https://github.com/awslabs/aws-lambda-powertools-python/issues/new?assignees=&labels=bug%2C+triage&template=bug_report.md&title=)** | **[Kitchen sink example](https://github.com/awslabs/aws-lambda-powertools-python/tree/develop/example)** | **[Detailed blog post](https://aws.amazon.com/blogs/opensource/simplifying-serverless-best-practices-with-lambda-powertools/)**
 
+> **Join us on the AWS Developers Slack at `#lambda-powertools`** - **[Invite, if you don't have an account](https://join.slack.com/t/awsdevelopers/shared_invite/zt-gu30gquv-EhwIYq3kHhhysaZ2aIX7ew)**
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 ## Features
 
 * **[Tracing](https://awslabs.github.io/aws-lambda-powertools-python/core/tracer/)** - Decorators and utilities to trace Lambda function handlers, and both synchronous and asynchronous functions