Initial documentation for the Monero libraries (#122)

* Document all features

* Largely document the Monero libraries

Relevant to https://github.com/serai-dex/serai/issues/103 and likely 
sufficient to get this removed from 
https://github.com/serai-dex/serai/issues/102.

coins/monero/src/ringct/hash_to_point.rs

@@ -2,6 +2,7 @@ use curve25519_dalek::edwards::EdwardsPoint;
 
 pub use monero_generators::{hash_to_point as raw_hash_to_point};
 
+/// Monero's hash to point function, as named `ge_fromfe_frombytes_vartime`.
 pub fn hash_to_point(key: EdwardsPoint) -> EdwardsPoint {
   raw_hash_to_point(key.compress().to_bytes())
 }