More detailed redirect information for some search-only forms

[stephenmk]

For example, 裏 is recorded as a hidden form in the entry for 内・うち because 裏 is mentioned in the note for the fourth sense.

I should check the notes for each entry with hidden forms. If I find a hidden form in a note, I should add the relevant information to the redirect entry so that users understand why they're being pointed e.g. from 裏 to 内.