Update docs for people struggling with "Please update your includePath. Squiggles are disabled for this translation unit"

[DevHusariaSolutions]

I found out how to make it work without issues.

1. Add includePath item for "libraries" Arduino directory.
2. Run command "Arduino: Initialize"
3. Run command "Arduino: Board manager" and install one for Your project
4. Run command "Arduino: Change board type" and select installed type of board

No restart of vscode was required to see that our error dissappears