[FO31] Typos in 17.3 'Functions that Operate on Arrays', as follows:

(1) 17.3.4 array:remove - Error Condition
     Should refer to argument $position --- rather than $index

(2) 17.3.8 array:reverse - Examples 
     2nd example returns [("c", "d"), ("a", "b")] --- rather than [("c", "d"), ("a", "b)"] (note misplaced quote)

(3) 17.3.11 array:filter - Examples 
     1st example, function variable $x (or $z) should match; 
          also returns [1,2] --- rather than ["A", "B"]

(4) 17.3.12 array:fold-left AND 17.3.13 array:fold-right - Signature 
     Result type is item()* --- rather than array(*)

(5) 17.3.15 array:sort - Rules 
     2nd rule "same members as the input **array** $input" -- rather than "... input **sequence** $input"