change single quotes to double quotes, and added documention for open file doc

docs/Open Files In An Editor.md

@@ -22,6 +22,7 @@ The following editors are currently supported by default.
 - `sublime`  - Sublime Text 2 and possibly 3 (on OS X you might need [a special handler](https://github.com/dhoulb/subl))
 - `textmate` - Textmate
 - `xdebug`   - xdebug (uses [xdebug.file_link_format](http://xdebug.org/docs/all_settings#file_link_format))
+- `vscode`   - VSCode (ref [Opening VS Code with URLs](https://code.visualstudio.com/docs/editor/command-line#_opening-vs-code-with-urls))
 
 Adding your own editor is simple:
 

src/Whoops/Handler/PrettyPageHandler.php

@@ -95,7 +95,7 @@ class PrettyPageHandler extends Handler
         "macvim"   => "mvim://open/?url=file://%file&line=%line",
         "phpstorm" => "phpstorm://open?file=%file&line=%line",
         "idea"     => "idea://open?file=%file&line=%line",
-        'vscode'   => "vscode://file/%file:%line",
+        "vscode"   => "vscode://file/%file:%line",
     ];
 
     /**