adds call for participation section

Signed-off-by: Nell Shamrell <[email protected]>

Author: nellshamrell

draft/2021-12-22-this-week-in-rust.md

@@ -58,6 +58,8 @@ Every week we highlight some tasks from the Rust community for you to pick and g
 
 Some of these tasks may also have mentors available, visit the task page for more information.
 
+* [diesel-rs - Documentation improvements](https://github.com/diesel-rs/diesel/pull/2996)
+
 If you are a Rust project owner and are looking for contributors, please submit tasks [here][guidelines].
 
 [guidelines]: https://users.rust-lang.org/t/twir-call-for-participation/4821