README note about install failure under "squash root" NFS
README note about install failure under "squash root" NFS

Summary: easy workaround

Reviewed By: ccheever

Test Plan: verify squash root NFS fails but local still works

Revert Plan: ok

AsafMah/phpsh,facebookarchive/phpsh,rhee/phpsh,chooaya/phpsh,rjmi004/phpsh,rjmi004/phpsh,terrorbox/phpsh,AsafMah/phpsh,rjmi004/phpsh,chooaya/phpsh,terrorbox/phpsh,rhee/phpsh,rhee/phpsh,terrorbox/phpsh,facebookarchive/phpsh,AsafMah/phpsh,chooaya/phpsh