Described type methods.
Linked type predicate methods to class descriptions.
Documented index-of & cousins.
Documented last-index-of & cousins.
Linked initial/final searching procedures.
Documented join.
Rephrased documentation for join.
Replaced occurances of 'array' with 'list'; described .sort[].
Documented filter & cousins.
Linked .reject to logical opposite.
Cleaned up argument omission.
Linked README.md to yak-lang.org