Improve this Doc

# Error: error:ihshprfx
Missing Hash Prefix

    Invalid url "{0}", missing hash prefix "{1}".

## Description

This error occurs when $location service is configured to use a hash prefix but this prefix was not present in a url that the `$location` service was asked to parse.

For example if you configure `$location` service with prefix `'!'`:

    myApp.config(function($locationProvider) {
      $locationProvider.hashPrefix('!');
    });

If you enter the app at url `http://myapp.com/#/myView` this error will be thrown.

The correct url for this configuration is `http://myapp.com/#!/myView` (note the `'!'` after `'#'` symbol).