Corrected the comment answer for the Day 4: Strings folder

[NinadRao0707]

I addressed the issue in the Day 4: Strings folder.

In the find() example, if find() returns the position first occurrence of 'y', then shouldn't it return 5 instead of 16? There was a wrong comment in the 04_strings.md file. So I corrected it and pushed it in my forked repository.

I will be glad if you merge my changes after reviewing my changes in the code. Thanks !