MOBILE-2995 book: Fix lint errors in book
MOBILE-2995 book: Fix lint errors in book

reskit/moodlemobile,moodlehq/moodlemobile2,reskit/moodlemobile,reskit/moodlemobile,moodlehq/moodlemobile2,reskit/moodlemobile,moodlehq/moodlemobile2,moodlehq/moodlemobile2,reskit/moodlemobile,moodlehq/moodlemobile2,reskit/moodlemobile,moodlehq/moodlemobile2