Vscode_deno: Rename Releases.md to CHANGELOG.md

[bxantus]

Is your feature request related to a problem? Please describe.

It would be beneficial for this project to use a changelog.
When new updates arrive, users can check what's new, what has changed, what steps are necessary to ensure the correct working of the extension.

Describe the solution you'd like

Create a CHANGELOG.md file next to README.md and update it at least when new releases are created.
vscode will automatically show the changes next to extension's documentation.

You can use Keep a Changelog for format.
Here's the changelog for one of my own extensions: https://github.com/bxantus/mdoc/blob/master/CHANGELOG.md

[lucacasonato]

We have a Releases.md file: https://github.com/denoland/vscode_deno/blob/main/Releases.md

[kitsonk]

@lucacasonato but if we moved it do CHANGELOG.md it would appear as part of the extension documentation, which makes it worth considering in my opinion.