message: add note about the requirements
diff: @@ -112,6 +112,8 @@ $ make
  $ make install
  ```
  +**Note:** If you use the cross compiler outside of this repository, the compiler uses per default the library operating systems located by the toolchain (e.g. `/opt/hermit/x86_64-hermit/lib/libhermit.a`).
  +
  ## Testing
  ### As multi-kernel within a virtual machine
  