This moves all the documentation under the doc/ tree for consistency.
Replace the link to include/spdk/env.h to raw text - the Doxygen
Markdown parser will automatically turn it into a link since it is a
Doxygen input file.
Change-Id: If6bde1cfc965cada2c741acd5505026545ad4cf7
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
