Cargo clippy warnings and update readme for standalone build

Author: nepoche

Cargo.lock

@@ -86,10 +86,10 @@ git clone git@github.com:webb-tools/protocol-substrate.git
 git submodule update --init
 ```
 
-Build the node in `release mode`:
+Build the standalone node in `release mode`:
 
 ```bash
-cargo build --release
+cargo build --release -p webb-standalone-node
 ```
 
 #### Troubleshooting for Apple Silicon users

README.md

@@ -3,7 +3,7 @@
 use std::sync::Arc;
 
 use codec::{Decode, Encode};
-use jsonrpc_core::{Error, ErrorCode, Result};
+use jsonrpc_core::{Result};
 use jsonrpc_derive::rpc;
 use sp_api::ProvideRuntimeApi;
 use sp_blockchain::HeaderBackend;

pallets/linkable-tree/rpc/src/lib.rs

@@ -338,7 +338,7 @@ pub mod pallet {
 		let default_zero = T::DefaultZeroElement::get();
 		temp_hashes.push(default_zero);
 		let mut temp_hash = default_zero.to_bytes().to_vec();
-		for i in 0..T::MaxTreeDepth::get() {
+		for _ in 0..T::MaxTreeDepth::get() {
 			temp_hash = T::Hasher::hash_two(&temp_hash, &temp_hash).unwrap();
 			temp_hashes.push(T::Element::from_vec(temp_hash.clone()));
 		}