docs: describe BucketFinder

lib_vector_search/include/bucket_finder.h

@@ -10,17 +10,34 @@ private:
   std::unordered_map<char, WordRefList> directory_;
 
 public:
+  /// Inserts references to all words from word_list between first_index and
+  /// last_index, including first_index, excluding last_index.
   void insert(const WordList &word_list, size_t first_index, size_t last_index);
 
+  /// Find all words that start with search_term
+  /// @return A list with references to the results.
   WordRefList find_prefix(std::string_view search_term) const;
 };
 
+/** This class provides efficient, parallel search over a list of strings.
+ *
+ * References to all input strings are stored in a tree-like structure that
+ * provides fast and lock-free parallel insertion and parallel (with minimal
+ * synchronization) search for all words that start with a given term.
+ */
 class BucketFinder : public Finder {
 private:
   std::vector<Bucket> buckets_;
 
 public:
+  /// Creates a BucketFinder over all words in word_list.
   BucketFinder(const WordList &word_list);
 
+  /// Find all words that start with search_term
+  /// @return A list with references to the results.
   WordRefList find_prefix(std::string_view search_term) const override;
+
+private:
+  /// Inserts references to all words from word_list.
+  void insert(const WordList &word_list);
 };