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/ringct/borromean/README.md

@@ -0,0 +1,12 @@
+# Monero Borromean
+
+Borromean ring signatures arranged into a range proof, as done by the Monero
+protocol.
+
+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).