Update for CC Mode 5.30 and incidental amendments.

Update for CC Mode 5.30 and incidental amendments.
("AWK"): Is consistently thus spelt throughout.
(AWK, Pike): Document as "C-like modes".
(@kbd{M-j}): Document as alternative to @kbd{C-M-j}.
(M-x man): Supersedes M-x manual-entry.
Add numerous index entries.  Correct "ESC a/e" to "M-a/e".

("Comments in C"): Delete node; the info is in CC Mode manual.
(c-comment-only-line-offset): Remove description.

(C-c ., C-c C-c): Describe new C Mode bindings.

(C-u TAB, indent-code-rigidly, c-indent-exp, c-tab-always-indent)
(@dfn{Style}, c-default-style, comment-column, comment-padding)
(c-up-conditional, c-beginning-of-statement, c-end-of-statement):
Amend definitions.

(c-beginning-of-defun, c-end-of-defun, c-context-line-break):
Describe functions.

(c-comment-start-regexp, c-hanging-comment-ender-p)
(c-hanging-comment-starter-p): Remove obsolete definitions.