Make docs.rs show the full feature set for the gitoid crate

[alilleybrinker]

Right now the docs.rs site for the gitoid crate (https://docs.rs/gitoid/latest/gitoid/) only shows the RustCrypto backend, so it's missing BoringSSL and OpenSSL. This should be fixed with some modified configuration in the Cargo.toml to instruct Docs.rs to use all features.