bug#21552: 25.0.50; doc of `isearch-search-fun-function'

[Drew Adams]

The doc string should say more about the function value.  It should
describe each of its parameters: STRING, BOUND, and NOERROR.

It should also say something about what is meant by "translation".
Apparently, when recent changes were made to isearch.el to support
character folding, "translation" was sprinkled here and there in this
file, with no explanation.  This should be remedied.


In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2015-09-23
Bzr revision: 325200ac1dcf5bed6918ea827d8a48d89487e083
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --host=i686-pc-mingw32 --enable-checking=yes,glyphs'