add wildcard mention

src/query/regex_query.rs

@@ -8,7 +8,10 @@ use tantivy_fst::Regex;
 
 /// A Regex Query matches all of the documents
 /// containing a specific term that matches
-/// a regex pattern.
+/// a regex pattern. 
+///
+/// Wildcard queries (e.g. ho*se) can be achieved
+/// by converting them to their regex counterparts.
 ///
 /// ```rust
 /// use tantivy::collector::Count;