All states in the thread state diagram were initial-cap except
"suspended". Make it Suspended for consistency.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
Moving all thread docs into 1 page was a bit too much. Split the section
a bit and remove redundant and useless sections and move some thread
related documentation from the scheduling page to threads (thread states
and priorities).
Add a new figure for thread states.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>