Move guides and APIs into separate directories and cleanup naming
introducing index files rather than named section files.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
fixed error introduced in application.rst (v1.8) along with a general
spelling check pass including consistent spelling of "runtime" and
hyphenated words with "pre-"
Signed-off-by: David B. Kinder <david.b.kinder@intel.com>
