Rename the coins folder to networks (#583)

* Rename the coins folder to networks

Ethereum isn't a coin. It's a network.

Resolves #357.

* More renames of coins -> networks in orchestration

* Correct paths in tests/

* cargo fmt

networks/monero/generators/README.md

@@ -0,0 +1,13 @@
+# Monero Generators
+
+Generators used by Monero in both its Pedersen commitments and Bulletproofs(+).
+An implementation of Monero's `hash_to_ec` is included, as needed to generate
+the generators.
+
+This library is usable under no-std when the `std` feature (on by default) is
+disabled.
+
+### Cargo Features
+
+- `std` (on by default): Enables `std` (and with it, more efficient internal
+  implementations).