Update description to prefer environment variable (Patch by online editor user)

Dear online editor user,

I lost your name when making some small changes to your patch. I did copy your details from the patch into my clipboard, but overwrote it when, being too lazy to type a whole word, I copied some other text in the editor. Your name may be forgotten, but your contribution remains.

Thank you, online editor user!

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@334284 c90b9560-bf6c-de11-be94-00142212c4b1