Update docs for proper usage of FakeFS::SpecHelpers
Update docs for proper usage of FakeFS::SpecHelpers

1234-/fakefs,openSUSE/fakefs,zimbatm/fakefs,vhl/fakefs,ktheory/fakefs,pivotal-cf-experimental/fakefs,marxarelli/fakefs,eventualbuddha/fakefs,dekz/fakefs,anthonyryan1/fakefs,moretea/fakefs,Flameeyes/fakefs,bf4/fakefs,defunkt/fakefs,onehub/fakefs,lgierth/fakefs,bquorning/fakefs,deployable/fakefs,fakefs/fakefs