MAINTAINERS: add entry for the Rust alloc module

Add maintainers entry for the Rust `alloc` module.

Currently, this includes the `Allocator` API itself, `Allocator`
implementations, such as `Kmalloc` or `Vmalloc`, as well as the kernel's
implementation of the primary memory allocation data structures, `Box`
and `Vec`.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-30-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: Danilo Krummrich

Diff for: MAINTAINERS

@@ -20230,6 +20230,13 @@ F:	scripts/*rust*
 F:	tools/testing/selftests/rust/
 K:	\b(?i:rust)\b
 
+RUST [ALLOC]
+M:	Danilo Krummrich <dakr@kernel.org>
+L:	rust-for-linux@vger.kernel.org
+S:	Maintained
+F:	rust/kernel/alloc.rs
+F:	rust/kernel/alloc/
+
 RXRPC SOCKETS (AF_RXRPC)
 M:	David Howells <dhowells@redhat.com>
 M:	Marc Dionne <marc.dionne@auristor.com>