Update the Open in VSCode button URL to construct a vscode-remote://dev-container URL to allow users to jump directly to the devcontainer inside VSCode.

This is an undocumented feature, but some enterprising folks have figured out how to do this: https://github.com/felipecrs/dotfiles/blob/master/home/dot_local/bin/executable_code#L113

More information on this URL format is available here: https://blog.lohr.dev/launching-dev-containers