ROFL: Document aes, sse3 errors

[matevz]

Either create a Troubleshooting section or somewhere under .cargo/config.toml codeblock, mention the

error: The following target_feature flags must be set: +aes,+ssse3.
  --> /home/oa/.cargo/registry/src/index.crates.io-6f17d22bba15001f/deoxysii-0.2.4/src/lib.rs:26:1
   |
26 | compile_error!("The following target_feature flags must be set: +aes,+ssse3.");
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

you get, if you forget to add the .cargo/config.toml file, so the error gets indexed if people will be searching for the error.