Detach the child process when waiting is false

On platforms that use xdg-open, if waiting option is false set stdio to 'ignore'
and detached to true so that the xdg-open process is completely detached from
the parent and it is able to continue running after the parent exits.

index.js

@@ -61,6 +61,10 @@ module.exports = (target, opts) => {
 			// `xdg-open` will block the process unless
 			// stdio is ignored even if it's unref'd
 			cpOpts.stdio = 'ignore';
+			// `xdg-open` will NOT stay running in the background after
+			// the parent exits unless it is detached from the parent AND it
+			// ignores the parent's stdio file descriptor 
+			cpOpts.detached = true;
 		}
 	}
 

readme.md

@@ -65,7 +65,7 @@ Type: `Object`
 Type: `boolean`<br>
 Default: `true`
 
-Wait for the opened app to exit before fulfilling the promise. If `false` it's fulfilled immediately when opening the app.
+Wait for the opened app to exit before fulfilling the promise. If `false` it's fulfilled immediately when opening the app, and the app is completely detached from the node process that spawned it.
 
 On Windows you have to explicitly specify an app for it to be able to wait.