bug#286: 23.0.60; doc string for yank-pop

[Drew Adams]

The doc string includes this:
 
 "When this command inserts killed text into the buffer, it honors
 `yank-excluded-properties' and `yank-handler' as described in the
 doc string for `insert-for-yank-1', which see."
 
This is the doc string for a user command. It should not tell users to
refer to the doc string of an internal function (`insert-for-yank-1').
 
And "When this command inserts killed text into the buffer" seems
redundant - that is what this command _always_ does, no?
 

In GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
 of 2008-05-04 on LENNART-69DE564
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags -Ic:/g/include
-fno-crossjumping'