* lisp/emacs-lisp/checkdoc.el: Remove redundant :group keywords.

* lisp/emacs-lisp/checkdoc.el: Remove redundant :group keywords.
Use #' instead of ' to quote functions.
(checkdoc-output-mode): Use setq-local.
(checkdoc-spellcheck-documentation-flag, checkdoc-ispell-lisp-words)
(checkdoc-verb-check-experimental-flag, checkdoc-proper-noun-regexp)
(checkdoc-common-verbs-regexp): Mark safe-local-variable.
(checkdoc-ispell, checkdoc-ispell-current-buffer)
(checkdoc-ispell-interactive, checkdoc-ispell-message-interactive)
(checkdoc-ispell-message-text, checkdoc-ispell-start)
(checkdoc-ispell-continue, checkdoc-ispell-comments)
(checkdoc-ispell-defun): Remove unused arg `take-notes'.