vscode-auto-open-markdown-preview | VSCode extension for opening Markdown

I wrote an extension for vscode. After installation the extension folder contains documentation in a markdown file. I want to provide a command that loads this file into the preview pane so it displays rendered with images and hyperlinks etc.

You can do this sort of thing interactively:

and I have the full path to the markdown file, so now all I need is details of the command that implements this context menu item.

Just the name of it would do, I'm sure bing or google can take it from there.

I thought I found it in this repo https://github.com/hnw/vscode-auto-open-markdown-preview/blob/master/src/extension.ts but it looks like the author got stumped at the same place - the constant for the command is an empty string.