(Syntax Table Functions): Clarify and correct descriptions of

(Syntax Table Functions): Clarify and correct descriptions of
make-syntax-table and copy-syntax-table.
(Motion and Syntax): Clarify SYNTAXES argument to skip-syntax-forward.
(Parsing Expressions): Mention that the return value of parse-partial-sexp
is currently a list of ten rather than nine elements.
(Categories): Various corrections and clarifications.