Changes to Cooperative Threading between r2 and r3

'''Cooperative Threading'''

This [threading] model is sometimes called "[fibers]". It is the threading model where each thread must ''explicitly'' give up control of the process or CPU to allow other threads to run. --> This [thread]ing model is sometimes called "[fibers]". It is the threading model where each thread must ''explicitly'' give up control of the process or CPU to allow other threads to run.

Legend

     Only in r2
     Only in r3
     -->      Modified slightly between r2 and r3