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/generators/src/hash_to_point.rs

@@ -7,7 +7,7 @@ use dalek_ff_group::field::FieldElement;
 
 use crate::hash;
 
-#[allow(dead_code)]
+/// Monero's hash to point function, as named `ge_fromfe_frombytes_vartime`.
 pub fn hash_to_point(bytes: [u8; 32]) -> EdwardsPoint {
   #[allow(non_snake_case)]
   let A = FieldElement::from(486662u64);