Revert "Build a more organized doc structure"

Our philosophy document is one of our most important documents
in he documentation repository.  I appreciate in general the notion
of reorganizing many of our docs, but this one should be left alone
and possibly protected by a roll-call vote in the future.

This reverts commit aa517c4b.

Change-Id: Ic17861e823095a1891ac25ddaf429b66e352e30e