(whitespace-check-buffer-leading, whitespace-check-buffer-trailing,

(whitespace-check-buffer-leading, whitespace-check-buffer-trailing,
whitespace-check-buffer-indent, whitespace-check-buffer-spacetab,
whitespace-check-buffer-ateol, whitespace-highlighted-space,
whitespace-check-leading-whitespace, whitespace-check-trailing-whitespace,
whitespace-check-spacetab-whitespace, whitespace-check-indent-whitespace,
whitespace-check-ateol-whitespace, whitespace-abort-on-error, whitespace-modes):
Fix typos in docstrings.
(defgroup, defcustom): Doc fix.