Update VS Code docs page's LS-related information

[jakebailey]

A number of things have changed since that page was last edited:

• The new LS has different configuration options.
• extraPaths needs to be recommended to specify import roots (Fix editable installs when using extraPaths/PYTHONPATH #1183).

And likely more.

Repo: https://github.com/microsoft/vscode-docs