Add vscode instructions to tools_editors

[jlperla]

On https://lectures.quantecon.org/jl/tools_editors.html

• [ ] We need to find a consistent way to have a julia startup file that works for both Atom, the REPL, the Debugger, and vscode. Might need to ask around
• [ ] Add installation instructions for vscode and setting up julia support
• [ ] Add similar sorts of quick walkthrough of editing code/ ctrl-enter to execute tests, etc.
• [ ] A little text about reasons Juno is superior for certain things.

[arnavs]

Issue is obsolete.

[jlperla]

Why is it obsolete?

[arnavs]

I thought we decided not to put in VS Code instructions. Maybe I'm hallucinating, though.

[jlperla]

This is a 1.2 issue, not a 1.03 or even 1.1