Add docs to support executing wh run from within vscode.

[rsyi]

We currently allow users to write --!wh-run in either SQL files or ````sqlblocks in Markdown files, and have this dynamically replaced with results of the surrounding query queries in-line whenwh run filename.sql` is run from the command-line.

See here for a description of this behavior: https://docs.whale.cx/features/running-sql-queries#running-sql-blocks-within-markdown-files

To make this really useful, we should docs to help users set up wh run FILENAME to a keybinding in their editor of choice. I've added some docs for vim already, here, but other editors would help provide coverage.

This ticket is for providing docs to support VScode implementation.