docs/contributing: remove stale comment on window.openFoldersInNewWindow

According to the snapshot of github.com/microsoft/vscode-go.wiki.git@5b702d8
(4years ago)

"This will open a new VS Code window which will have the title `[Extension Development Host]`. In this window, open any folder with Go code. Make sure the `window.openFoldersInNewWindow` setting is not `"on"`, otherwise a new, non-`[Extension Development Host]`, window may be opened."

I cannot reproduce this problem with today's vscode.

Remove this sentence to avoid distraction.

Fixes #190

Change-Id: Ie1f1cd916c6a48e8f7e6fde618bc621ce2396a22
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/410898
Reviewed-by: Suzy Mueller <[email protected]>

Author: hyangah

docs/contributing.md

@@ -63,8 +63,6 @@ The debugging feature documentation has a dedicated section for tips for develop
     code .
     ```
 
-3) Make sure the `window.openFoldersInNewWindow` setting is not `"on"`.
-
 #### Lint
 
 You can run `npm run lint` on the command-line to check for lint errors in your program. You can also use the [TSLint](https://marketplace.visualstudio.com/items?itemName=ms-vscode.vscode-typescript-tslint-plugin) plugin to see errors as you code.