MAINTAINERS: add Andreas Hindborg as Rust reviewer

Andreas has been involved with the Rust for Linux project for more than
a year now. He has been primarily working on the Rust NVMe driver [1],
presenting it in several places (such as LPC [2][3] and Kangrejos [4]).

In addition, he recently submitted the Rust null block driver [5] and
has been reviewing patches in the mailing list for some months.

Thus add him to the `RUST` entry as reviewer.

Link: https://rust-for-linux.com/nvme-driver [1]
Link: https://lpc.events/event/16/contributions/1180/attachments/1017/1961/deck.pdf [2]
Link: https://www.youtube.com/watch?v=BwywU1MqW38 [3]
Link: https://kangrejos.com/A%20Linux%20(PCI)%20NVMe%20Driver%20in%20Rust.pdf [4]
Link: https://lore.kernel.org/rust-for-linux/20230503090708.2524310-1-nmi@metaspace.dk/ [5]
Acked-by: Andreas Hindborg <a.hindborg@samsung.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20230718054426.1048583-1-ojeda@kernel.orgSigned-off-by: Miguel Ojeda <ojeda@kernel.org>

MAINTAINERS

@@ -18554,6 +18554,7 @@ R:	Boqun Feng <boqun.feng@gmail.com>
 R:	Gary Guo <gary@garyguo.net>
 R:	Björn Roy Baron <bjorn3_gh@protonmail.com>
 R:	Benno Lossin <benno.lossin@proton.me>
+R:	Andreas Hindborg <a.hindborg@samsung.com>
 L:	rust-for-linux@vger.kernel.org
 S:	Supported
 W:	https://github.com/Rust-for-Linux/linux