docs: Add clang to dependency list for building ROFL

A discord user reported issue on fresh Ubuntu 24.04 that compiling
ROFL fails during the compilation of mbedtls-sys-auto crate, if clang
is not install on the host.

docs/rofl/prerequisites.md

@@ -85,11 +85,12 @@ rust environment:
 rustup target add x86_64-unknown-linux-musl
 ```
 
-Additionally, you will need the MUSL wrapper for gcc and the multilib package.
-On Ubuntu/Debian systems, you can install it by running:
+Additionally, you will need the MUSL wrapper for gcc, the multilib package and
+clang for compiling the `mbedtls-sys-auto` dependency. On Ubuntu/Debian systems,
+you can install those by running:
 
 ```shell
-sudo apt install musl-tools gcc-multilib
+sudo apt install musl-tools gcc-multilib clang
 ```
 
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