string_list: document string_list_(insert,lookup)

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

string-list.h

@@ -55,9 +55,19 @@ void string_list_remove_empty_items(struct string_list *list, int free_util);
 int string_list_has_string(const struct string_list *list, const char *string);
 int string_list_find_insert_index(const struct string_list *list, const char *string,
 				  int negative_existing_index);
+/*
+ * Inserts the given string into the sorted list.
+ * If the string already exists, the list is not altered.
+ * Returns the string_list_item, the string is part of.
+ */
 struct string_list_item *string_list_insert(struct string_list *list, const char *string);
 struct string_list_item *string_list_insert_at_index(struct string_list *list,
 						     int insert_at, const char *string);
+
+/*
+ * Checks if the given string is part of a sorted list. If it is part of the list,
+ * return the coresponding string_list_item, NULL otherwise.
+ */
 struct string_list_item *string_list_lookup(struct string_list *list, const char *string);
 
 /*