added instructions about how to install the C extension
added instructions about how to install the C extension

jpauli/Pimple,gomboc/Pimple,fabpot/Pimple,jbboehr/Pimple,RustJason/Pimple,silexphp/Pimple,fabpot/Pimple,RustJason/Pimple,michabbb-backup/Pimple,gomboc/Pimple,arduanov/Pimple,mnapoli/simplex,jbboehr/Pimple,arduanov/Pimple,jpauli/Pimple,jpauli/Pimple