s:check_users_value() returns help suggestions that do not exist for options

[agude]

For example, when I mis-set diary_rel_path (as in #684), it gives the error:

Vimwiki Error: The provided value '' of the option 'diary_rel_path' in g:vimwiki_list must have at least 1 character(s) but has 0. See ':h g:vimwiki_diary_rel_path'.

But running :h g:vimwiki_diary_rel_path gives the error:

E149: Sorry, no help for g:vimwiki_diary_rel_path

Instead, it should suggest:

:h vimwiki-option-diary_rel_path

[ranebrown]

Thanks for pointing this out. There is a common function used for printing the error messages that needs updated for the wikilocal options. If you can make the change as part of your PR for #684 that would be great.

[agude]

I'll give this one a go, but I suspect it will take me a bit to wrap my head around it.