bug#14842: 24.3.50; doc strings of `next-line', `previous-line'

[Drew Adams]

The doc strings need to describe the input parameters to the function.
In particular, nothing is said about TRY-VSCROLL.

(And no, this function is not excluded from use in Lisp.  See the first
word of the second doc-string sentence ("Interactively"), and read the
rationale for the advice in the last paragraph.)

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-07-01 on LEG570
Bzr revision: 113246 lekktu@gmail.com-20130701165437-ea20s94hqwp3ttaj
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/usr --enable-checking CFLAGS='-O0 -g3'
 CPPFLAGS='-DGLYPH_DEBUG=1 -I/c/usr/include''