Update templates.md

This is wrong:

```
The following example creates a `@datetime($var)` directive which simply calls `->format()` on `$var`:

	Blade::extend(function($view, $compiler)
	{
		$pattern = $compiler->createMatcher('datetime');

		return preg_replace($pattern, '$1<?php echo $2->format('m/d/Y H:i'); ?>', $view);
	});

```
This has 2 errors in it:

1. ``'m/d/Y H:i'`` isn't properly escaped.

2. ``@datetime($var)`` becomes ``($var)->format()`` and crashes instead of ``$var->format()``

Previous discussion: https://github.com/laravel/framework/issues/4770 and https://github.com/laravel/docs/pull/835