Enable php_openssl.dll in php.ini

it specifies to enable the extension php_openssl.dll in php.ini. When php_openssl.gll is disabled, the command show an error in the function file_get_contents but not specify that is necesary to enable php.ini.
Update 00-intro.md
Merge pull request #1903 from jos101/patch-2

Enable php_openssl.dll in php.ini