Update php production guides

[sanderson]

Currently all the production php guides recommend using php-server as web start commands. The problem with this approach is that runit, the process manager views the multiple processes started as a single process. If one of them dies, it won't restart it.

The better approach would be to use two separate start commands:

Using Apache

web.site:
  start:
    php: start-php
    apache: start-apache

Using Nginx

web.site:
  start:
    php: start-php
    nginx: start-nginx