Problem: tests: string options in gen_opt_test.vim aren't fully sorted.
Solution: Sort the string options alphabetically. Also make description
of 'maxsearchcount' start with lower-case for consistency with
other options, update documentation for searchcount().
closes: #17720
Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>