Add cost of formatting blog post

Author: James Munns

content/2020-01-01-newsletter-22.md

@@ -31,11 +31,14 @@ If you want to mention something in [the next newsletter], send us a pull reques
 - [@andre-richter] added a new tutorial for the `Operating System development tutorials in Rust on the Raspberry Pi` series:
     - Tutorial 13: [Integrated Testing](https://github.com/rust-embedded/rust-raspi3-OS-tutorials/tree/master/13_integrated_testing) - Kernel `Unit tests`, `Integration tests` and `Console tests` using `QEMU`.
 - [@jamesmunns] sketched out a few introductory notes about foundational Embedded Rust Crates like `r0`, `cortex-m`, `PAC`s, and `HAL`s. See [part 1] and [part 2] on Twitter!
+- [@jamesmunns] wrote about the cost of [Formatting in Embedded Rust] as part of the [#rust2020] effort, and how to reduce code size while maintaining panic debug-ability
 - [Craig Bishop] wrote an overview of [Getting Started on the STM32L0], which contains an excellent breakdown of what makes up an Embedded Rust project
 
 [@jamesmunns]: https://twitter.com/bitshiftmask
 [part 1]: https://twitter.com/bitshiftmask/status/1210714309124186112
 [part 2]: https://twitter.com/bitshiftmask/status/1211031300531986432
+[Formatting in Embedded Rust]: https://jamesmunns.com/blog/fmt-unreasonably-expensive/
+[#rust2020]: https://twitter.com/hashtag/rust2020
 [Craig Bishop]: https://github.com/craigjb
 [Getting Started on the STM32L0]: https://craigjb.com/2019/12/31/stm32l0-rust/