Update "Building Your own Phar" section of README
Update "Building Your own Phar" section of README

As indicated in issue #357 the Box Project Installer reference is broken
cassiosantos/migrations,webonyx/migrations,ecolinet/migrations,boteeka/migrations,TomasVotruba/migrations,localheinz/migrations,TomasVotruba/migrations,webonyx/migrations,gencer/migrations,whiteoctober/migrations,doctrine/migrations,whiteoctober/migrations,ecolinet/migrations,localheinz/migrations,doctrine/migrations,gencer/migrations,mikeSimonson/migrations,mikeSimonson/migrations,boteeka/migrations