Added quick docs about ext- requirements
Added quick docs about ext- requirements
OKAMca/heroku-buildpack-php,penciu/apache,OKAMca/heroku-buildpack-php,stof/heroku-buildpack-php,penciu/apache,mraymond/heroku-buildpack-php,jstacoder/heroku-buildpack-php-1,Jonatasmz/php-buildpack,Scalingo/php-buildpack,AlphaStaxLLC/heroku-buildpack-php-custom,CHH/heroku-buildpack-php,CHH/heroku-buildpack-php,stof/heroku-buildpack-php,cachethq/cachet-buildpack,Scalingo/php-buildpack,CHH/heroku-buildpack-php,ryosuzuki/php-buildpack,Jonatasmz/php-buildpack,penciu/apache,pierredup/packager-buildpack-php,pierredup/packager-buildpack-php,Scalingo/php-buildpack,ryosuzuki/php-buildpack,OKAMca/heroku-buildpack-php,stof/heroku-buildpack-php,AlphaStaxLLC/heroku-buildpack-php-custom,jstacoder/heroku-buildpack-php-1,nsg/dokku-buildpack-picocms,nsg/dokku-buildpack-picocms,mraymond/heroku-buildpack-php,AlphaStaxLLC/heroku-buildpack-php-custom