Add Shining Knight's Ring to Homebrew Items list

[cfi2017]

As stated in this document:
https://docs.google.com/document/d/1OLbek7ZOng-ecG3ACTC3TWaN8Sluw4yyj7O0ERnWCXI/edit?usp=sharing

Make sure to add the item to the index at the top of the page as well.