Add reference to Merb configuration options list to #config method docs.
Add reference to Merb configuration options list to #config method docs.

wycats/merb,benburkert/merb-core,merb/merb,wycats/merb,wycats/merb,wycats/merb,merb/merb,wycats/merb,benburkert/merb-core,merb/merb