Update docs w/ forum links (swiftlang#1143)

Update the documentation with links to the VS Code extension section on
the forums.

Author: plemarquand

CONTRIBUTING.md

@@ -70,7 +70,7 @@ Please ensure to include the following in your Pull Request (PR):
 - Documentation on how these changes are being tested
 - Additional tests to show your code working and to ensure future changes don't break your code.
 
-Please keep your PRs to a minimal number of changes. If a PR is large, try to split it up into smaller PRs. Don't move code around unnecessarily as it makes comparing old with new very hard. If you have plans for a large change please talk to the maintainers of the project beforehand. There is a `#vscode-swift` channel on the Swift Server Slack. You can [join here](https://join.slack.com/t/swift-server/shared_invite/zt-5jv0mzlu-1HnA~7cpjL6IfmZqd~yQ2A).
+Please keep your PRs to a minimal number of changes. If a PR is large, try to split it up into smaller PRs. Don't move code around unnecessarily as it makes comparing old with new very hard. If you have plans for a large change please talk to the maintainers of the project beforehand either on the [swift.org forums](https://forums.swift.org) in the [VS Code Swift Extension category](https://forums.swift.org/c/related-projects/vscode-swift-extension/) or in the `#vscode-swift` channel on the Swift Server Slack. You can [join the Slack workspace here](https://join.slack.com/t/swift-server/shared_invite/zt-5jv0mzlu-1HnA~7cpjL6IfmZqd~yQ2A).
 
 ### Testing
 

README.md

@@ -14,7 +14,7 @@ Swift support uses [SourceKit LSP](https://github.com/apple/sourcekit-lsp) for t
 
 The extension is developed by members of the Swift Community and maintained by the [SSWG](https://www.swift.org/sswg/). The aim is to provide a first-class, feature complete extension to make developing Swift applications on all platforms a seamless experience.
 
-If you experience any issues or want to propose new features please [create an issue](https://github.com/swiftlang/vscode-swift/issues/new) or post on the `#vscode-swift` channel on [Slack](https://swift-server.slack.com).
+If you experience any issues or want to propose new features please [create an issue](https://github.com/swiftlang/vscode-swift/issues/new) or post on the [swift.org forums](https://forums.swift.org) in the [VS Code Swift Extension category](https://forums.swift.org/c/related-projects/vscode-swift-extension/).
 
 ## Contributing