3.0 - Remove php opening tag from php-only examples, correct recipes...

... add output codeblock language

Removed opening `<?php` tag from code examples throughout the documentation that contains PHP-only code.  The documentation examples largely do not include the opening tag.  Also changed the language definition for the "recipes add" output - it was defined as PHP when it's actually HTML.

 If this is :+1:, I can circle back on the 2.0 documentation.