feat(readme): deprecate Gitter in favor of cdk.dev Slack (aws#10700)

Shift community chat from Gitter to the cdk.dev Slack workspace


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

.github/ISSUE_TEMPLATE.md

@@ -31,4 +31,4 @@ falling prey to the [X/Y problem][2]!
 
 
 ### Other information
-<!-- e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. associated pull-request, stackoverflow, gitter, etc -->
+<!-- e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. associated pull-request, stackoverflow, slack, etc -->

.github/ISSUE_TEMPLATE/bug.md

@@ -41,7 +41,7 @@ What is the unexpected behavior you were seeing? If you got an error, paste it h
 
 ### Other
 
-<!-- e.g. detailed explanation, stacktraces, related issues, suggestions on how to fix, links for us to have context, eg. associated pull-request, stackoverflow, gitter, etc -->
+<!-- e.g. detailed explanation, stacktraces, related issues, suggestions on how to fix, links for us to have context, eg. associated pull-request, stackoverflow, slack, etc -->
 
 
 

.github/ISSUE_TEMPLATE/feature-request.md

@@ -31,7 +31,7 @@ labels: feature-request, needs-triage
 
 <!-- 
 e.g. detailed explanation, stacktraces, related issues, suggestions on how to fix, 
-links for us to have context, eg. associated pull-request, stackoverflow, gitter, etc
+links for us to have context, eg. associated pull-request, stackoverflow, slack, etc
 -->
 
 

.github/ISSUE_TEMPLATE/general-issues.md

@@ -32,4 +32,4 @@ falling prey to the [X/Y problem][2]!
 
 
 ### Other information
-<!-- e.g. detailed explanation, stacktraces, related issues, suggestions on how to fix, links for us to have context, eg. associated pull-request, stackoverflow, gitter, etc -->
+<!-- e.g. detailed explanation, stacktraces, related issues, suggestions on how to fix, links for us to have context, eg. associated pull-request, stackoverflow, slack, etc -->

README.md

@@ -1,7 +1,6 @@
 # AWS Cloud Development Kit (AWS CDK)
 
 ![Build Status](https://codebuild.us-east-1.amazonaws.com/badges?uuid=eyJlbmNyeXB0ZWREYXRhIjoiSy9rWmVENzRDbXBoVlhYaHBsNks4OGJDRXFtV1IySmhCVjJoaytDU2dtVWhhVys3NS9Odk5DbC9lR2JUTkRvSWlHSXZrNVhYQ3ZsaUJFY3o4OERQY1pnPSIsIml2UGFyYW1ldGVyU3BlYyI6IlB3ODEyRW9KdU0yaEp6NDkiLCJtYXRlcmlhbFNldFNlcmlhbCI6MX0%3D&branch=master)
-[![Gitter chat](https://badges.gitter.im/gitterHQ/gitter.svg)](https://gitter.im/awslabs/aws-cdk)
 [![Gitpod Ready-to-Code](https://img.shields.io/badge/Gitpod-ready--to--code-blue?logo=gitpod)](https://gitpod.io/#https://github.com/aws/aws-cdk)
 [![NPM version](https://badge.fury.io/js/aws-cdk.svg)](https://badge.fury.io/js/aws-cdk)
 [![PyPI version](https://badge.fury.io/py/aws-cdk.core.svg)](https://badge.fury.io/py/aws-cdk.core)
@@ -130,11 +129,9 @@ If you have a support plan with AWS Support, you can also create a new [support
 
 You may also find help on these community resources:
 * Look through the [API Reference](https://docs.aws.amazon.com/cdk/api/latest/docs/aws-construct-library.html) or [Developer Guide](https://docs.aws.amazon.com/cdk/latest/guide)
+* The #aws-cdk Slack channel in [cdk.dev](https://cdk.dev)
 * Ask a question on [Stack Overflow](https://stackoverflow.com/questions/tagged/aws-cdk)
   and tag it with `aws-cdk`
-* Come join the AWS CDK community on [Gitter](https://gitter.im/awslabs/aws-cdk)
-* Talk in the CDK channel of the [AWS Developers Slack workspace](https://awsdevelopers.slack.com) (invite required)
-* A community-driven Slack channel is also available, invite at [cdk.dev](https://cdk.dev)
 
 ### Roadmap