; Improve doc strings in whitespace.el

; Improve doc strings in whitespace.el

* lisp/whitespace.el (whitespace-hspace-regexp)
(whitespace-space-regexp, whitespace-tab-regexp)
(whitespace-trailing-regexp, whitespace-space-before-tab-regexp)
(whitespace-indentation-regexp, whitespace-empty-at-bob-regexp)
(whitespace-empty-at-eob-regexp)
(whitespace-space-after-tab-regexp)
(whitespace-big-indent-regexp, whitespace-line-column)
(whitespace-display-mappings, whitespace-global-modes)
(whitespace-action, whitespace-style, whitespace-space)
(whitespace-hspace, whitespace-tab, whitespace-trailing)
(whitespace-space-before-tab, whitespace-indentation)
(whitespace-big-indent, whitespace-empty)
(whitespace-space-after-tab): Doc fixes.