message: add hint to build "panic_abort"
diff: @@ -88,7 +88,7 @@ fn main() {
  The final step is building the application as follows:
  ```sh
  -cargo build -Z build-std=std,core,alloc --target x86_64-unknown-hermit
  +cargo build -Z build-std=std,core,alloc,panic_abort --target x86_64-unknown-hermit
  ```
  If the command failed with the error message
  @@ -100,12 +100,12 @@ linker `rust-lld` not found
  the path to the *llvm-tools* is not set.
  On Linux, it is typically installed at *${HOME}/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/bin*.
  ```sh
  -PATH=${HOME}/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/bin:$PATH cargo build -Z build-std=std,core,alloc --target x86_64-unknown-hermit
  +PATH=${HOME}/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/bin:$PATH cargo build -Z build-std=std,core,alloc,panic_abort --target x86_64-unknown-hermit
  ```
  Otherwise, the linker can be replaced by *lld* as follows:
  ```sh
  -RUSTFLAGS="-C linker=lld" cargo build -Z build-std=std,core,alloc --target x86_64-unknown-hermit
  +RUSTFLAGS="-C linker=lld" cargo build -Z build-std=std,core,alloc,panic_abort --target x86_64-unknown-hermit
  ```
  ## Running RustyHermit
  @@ -181,7 +181,7 @@ git clone https://github.com/hermitcore/rusty-hermit.git
  cd rusty-hermit
  git submodule init
  git submodule update
  -cargo build -Z build-std=std,core,alloc --target x86_64-unknown-hermit
  +cargo build -Z build-std=std,core,alloc,panic_abort --target x86_64-unknown-hermit
  ```
  ## Use RustyHermit for C/C++, Go, and Fortran applications
  