Bad help text link to civicrm wiki on custom search options form

This screen shot says it all: https://skitch.com/gregoryheller/gggki/custom-search-options-richard-hugo-house
when you are on this form which lets you add a custom search civicrm/admin/options/custom_search?group=custom_search&action=add&reset=1 there is a link to "learn more..." and that link leads to a non existent wiki page.

The "class path" is also pretty confusing (as it is not really described well), and the language around it, and the help docs on the wiki seem to conflict with or gloss over some details about creating your custom php files directory AND your extensions directory (where it seems civicrm was actually looking for my custom search file).