Errata in Ch15 ~ Ch18

[rickiepark]

• p537: 10th line from the bottom "randomly dropped at every iteration" should be changed "randomly dropped at every sample".
• p601: 9th line from the bottom /code/ch16 should be changed /tree/master/ch16.
• p677: 12th line from the bottom "$ St $ and $ R{t+1} $" should be changed "$ S{t+1} $ and $ R{t+1} $"
• p685: last eq. r' should be r
• p686: last line r' should be r
• p706: 6th line from the bottom _choose_action() should be choose_action()
• p711: 6th line in Note max_len should be maxlen

Ch18 gives good summary of Sutton's book. I hope that more topics will be covered in next edition. :) Thanks.

[rasbt]

Thanks a lot for the feedback. Will fix these things in the next edition :).