The following index combines the topical index you typically find at the beginning of a book with a descriptive word index (the details index) you typically find at the end of a book.  The topical index is top-down, and the descriptive word index is bottom-up.  The entries are in alphabetical order, with topical index items all capitalized, and descriptive word index items in lowercase.  You can then pick  the method you find most helpful or perhaps combine the two.  There are no page numbers necessary (as you would have in a book), since both the topical index items and the descriptive word index items are hyperlinks.