Fix typos in Chapter 6

 * interesing -> interesting
 * penalities -> penalties
 * practioner -> practitioner
 * favour -> favor
 * truely -> truly
 * eliminiates -> eliminates
 * reseachers -> researchers
 * favour -> favor
 * modelling -> modeling
 * responsiblitiy -> responsibility
 * tobacoo -> tobacco
 * Emprical -> Empirical
 * choosen -> chosen
 * knowledege -> knowledge
 * equivilant -> equivalent
 * pracitioner -> practitioner
 * paramters -> parameters
 * beween -> between
 * probabilties -> probabilities
 * recomment -> recommend
 * Mutlit-armed -> Multi armed
 * thier -> their
 * happing -> happening
 * restict -> restrict
 * pracitioners -> practitioners
 * Individiuals -> Individuals
 * favour -> favor
 * enourmous -> enormous
 * ealier -> earlier
 * anaylsis -> analysis
 * enviroment -> environment
 * aquire -> acquire
 * effectivly -> effectively
 * atleast -> at least
 * covaraince -> covariance
 * modifiying -> modifying
 * degress -> degrees
 * instabilty -> instability
 * garunteed -> guaranteed
 * practioner's -> practitioner's
 * strucutures -> structures
 * convience -> convenience
 * choosen -> chosen
 * forgetfullness -> forgetfulness
 * probablistic -> probabilistic
 * probabilitistic -> probabilistic
 * Equivilantly -> Equivalently
 * interesing disucssion -> interesting discussion

Author: pablooliveira