In 5.2 , wildcard match was added to be interoperable with Excel's matching syntax (and 5.3 made it default ). But the help still does not explain what wildcards are - see e.g. MATCH , which does not provide a clickable link on "wildcards"; and typing "wildcards" in help search gives a link to regular expressions  - even the help entry name in the right-hand "Contents" panel is "Using Wildcards in Text Searches".
We have an issue which mentions the need to provide help for wildcards in Find & Replace (bug 103587); this one is not related to F&R, but for spreadsheet functions. Note how the term "wildcards" is confusing - e.g., it's used in bug 91336 to denote regular expressions.
FTR: release notes for 5.2 document the wildcard syntax; related MS documentation is at  (it tells it is related to filters - see bug 121854 - and searches), and also in related spreadsheet function documentation: e.g.,  for MATCH.
I included some (hopefully) useful material about wildcards in the 7.0 Calc Guide. This could be used as the basis of a help page on the topic.