small README fixes around usage
small README fixes around usage

a2service/heroku-buildpack-php,heroku/heroku-buildpack-php,martijngastkemper/heroku-buildpack-php,puteulanus/heroku-buildpack-php,emeth-/heroku-buildpack-php,jayelkaake/heroku-buildpack-magento,heroku/heroku-buildpack-php,emeth-/heroku-buildpack-php,dzuelke/heroku-buildpack-php,rikur/heroku-buildpack-php,rikur/heroku-buildpack-php,createmultimedia/heroku-buildpack-php,martijngastkemper/heroku-buildpack-php,createmultimedia/heroku-buildpack-php,dzuelke/heroku-buildpack-php,0ppy/sample-buildpack,rs-makino/buildpack-test,0ppy/sample-buildpack,heroku/heroku-buildpack-php,thecsea/heroku-buildpack-php-with-ioncube,flant/heroku-buildpack-php,0ppy/sample-buildpack,rs-makino/buildpack-test,rs-makino/buildpack-test,puteulanus/heroku-buildpack-php,emeth-/heroku-buildpack-php,alzheic/heroku-buildpack-aop,a2service/heroku-buildpack-php,heroku/heroku-buildpack-php,rikur/heroku-buildpack-php,alzheic/heroku-buildpack-aop,createmultimedia/heroku-buildpack-php,jayelkaake/heroku-buildpack-magento,rs-makino/buildpack-test,rikur/heroku-buildpack-php,thecsea/heroku-buildpack-php-with-ioncube,emeth-/heroku-buildpack-php,flant/heroku-buildpack-php,rs-makino/buildpack-test,alzheic/heroku-buildpack-aop,thecsea/heroku-buildpack-php-with-ioncube,puteulanus/heroku-buildpack-php,jayelkaake/heroku-buildpack-magento,flant/heroku-buildpack-php,a2service/heroku-buildpack-php,rs-makino/buildpack-test,dzuelke/heroku-buildpack-php