add note about thanks

Author: steveklabnik

_posts/2017-03-16-Rust-1.16.md

@@ -313,5 +313,9 @@ See the [detailed release notes][notes] for more.
 
 ### Contributors to 1.16.0
 
+Last release, we introduced [thanks.rust-lang.org](https://thanks.rust-lang.org).
+We have been doing some behind-the-scenes refactoring work to allow for more projects
+than only Rust itself; we're hoping to introduce that in the next release.
+
 We had 137 individuals contribute to Rust 1.16.
 [Thanks!](https://thanks.rust-lang.org/rust/1.16.0)