String.LastIndexOf(needle, startIndex) behavior would benefit from some clarification

If we call`"abcabcabc".LastIndexOf("abc", 4)` we might reasonably expect it to return 3, having assessed the character at start index 4 to be 'b' and thus not equal to 'a' of the needle, and moved one position towards the start, where we can find 'a', 'b' and 'c' in indexes 3, 4 and 5 respectively

LastIndexOf actually returns 0, indicating the first match found is the "abc" at the start of the string. A comment in the source code explains the behavior, namely that LastIndexOf() overloads taking a startIndex do not consider characters to the right of the character at startIndex (so for a startIndex of 4, the trailing characters "cabc" are not searched/do not contribute towards finding a match; the search is executed as if the haystack is a Substring terminating after the startIndex character I.e. "abcab")

The current wording of the documentation only states where searching begins and states the direction but I believe it would benefit from an addition that explains the scope of the search doesn't extend to looking for characters to the right of startIndex