Announce bare-metal aarch64 rust-std support

Not sure about the "See it in action here" bullet point. Please remove it if you don't find it useful. I am unsure about it.

Author: andre-richter

content/2020-02-29-newsletter-24.md

@@ -47,6 +47,9 @@ TODO Add news related to embedded Rust that are not about new crates releases he
 - [@hannobraun][@braun-embedded] wrote an [article about his DW1000 driver][dw1000].
 - [@andre-richter] added a new tutorial to the [Operating System development tutorials in Rust on the Raspberry Pi] series:
   - [Tutorial 14: Exceptions Part 2: Peripheral IRQs] - Including drivers for the BCM and GICv2 interrupt controllers.
+- In recent nightlies,`rust-std` support for the two `bare-metal` `aarch64` targets [has landed][aarch64-rust-std].
+  - Add them using `rustup target add aarch64-unknown-none-softfloat` or `rustup target add aarch64-unknown-none`.
+  - [See it in action here][os-dev-rust-std] for building a kernel without the need for third-party tools like `xbuild` or `xargo`.
 
 ## Embedded Projects
 
@@ -96,6 +99,8 @@ TODO: Put all links for content here.
 [dw1000]: https://braun-embedded.com/dw1000/
 [Operating System development tutorials in Rust on the Raspberry Pi]: https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials
 [Tutorial 14: Exceptions Part 2: Peripheral IRQs]: https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials/tree/master/14_exceptions_part2_peripheral_IRQs
+[aarch64-rust-std]: https://github.com/rust-lang/rust/pull/68334
+[os-dev-rust-std]: https://github.com/rust-embedded/rust-raspberrypi-OS-tutorials/commit/c4f9432e131f6aa6dd58b9ba795d67ec3bfd3c7f
 
 ## `embedded-hal` Ecosystem Crates