Fix typos in Chapter 5

 * unecessary  -> unnecessary
 * etimation -> estimation
 * succiently -> succinctly
 * vaugely -> vaguely
 * agnogstic -> agnostic
 * convience, -> convenience,
 * occcur -> occur
 * suffiently-far-away -> sufficiently-far-away
 * forcasters -> forecasters
 * practial -> practical
 * esimate -> estimate
 * garunteed -> guaranteed
 * possibe -> possible
 * intution -> intuition
 * theshold -> threshold
 * positerior -> posterior
 * caluculate -> calculate
 * acccurate approximiation -> accurate approximation
 * Infact -> In fact
 * simplier -> simpler
 * equilivant -> equivalent
 * agnogstic -> agnostic
 * equivilantly -> equivalently
 * honour -> honor
 * permisson, -> permission,
 * attemps -> attempts
 * seperate -> separate
 * ellipicity -> ellipticity
 * simplicty -> simplicity
 * infact -> in fact
 * fouth -> fourth

Author: pablooliveira