docs: add README for RPC CLI example

Author: vladimirfomene

example-crates/example_bitcoind_rpc_polling/README.md

@@ -0,0 +1,68 @@
+# Example RPC CLI
+
+### Simple Regtest Test
+
+1. Start local regtest bitcoind.
+   ```
+    mkdir -p /tmp/regtest/bitcoind
+    bitcoind -regtest -server -fallbackfee=0.0002 -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> -datadir=/tmp/regtest/bitcoind -daemon
+   ```
+2. Create a test bitcoind wallet and set bitcoind env.
+   ```
+   bitcoin-cli -datadir=/tmp/regtest/bitcoind -regtest -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> -named createwallet wallet_name="test"
+   export RPC_URL=127.0.0.1:18443
+   export RPC_USER=<your-rpc-username>
+   export RPC_PASS=<your-rpc-password>
+   ```
+3. Get test bitcoind wallet info.
+   ```
+   bitcoin-cli -rpcwallet="test" -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> -datadir=/tmp/regtest/bitcoind -regtest getwalletinfo
+   ```
+4. Get new test bitcoind wallet address.
+   ```
+   BITCOIND_ADDRESS=$(bitcoin-cli -rpcwallet="test" -datadir=/tmp/regtest/bitcoind -regtest -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> getnewaddress)
+   echo $BITCOIND_ADDRESS
+   ```
+5. Generate 101 blocks with reward to test bitcoind wallet address.
+   ```
+   bitcoin-cli -datadir=/tmp/regtest/bitcoind -regtest -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> generatetoaddress 101 $BITCOIND_ADDRESS
+   ```
+6. Verify test bitcoind wallet balance.
+   ```
+   bitcoin-cli -rpcwallet="test" -datadir=/tmp/regtest/bitcoind -regtest -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> getbalances
+   ```
+7. Set descriptor env and get address from RPC CLI wallet.
+   ```
+   export DESCRIPTOR="wpkh(tprv8ZgxMBicQKsPfK9BTf82oQkHhawtZv19CorqQKPFeaHDMA4dXYX6eWsJGNJ7VTQXWmoHdrfjCYuDijcRmNFwSKcVhswzqs4fugE8turndGc/1/*)"
+   cargo run -- --network regtest address next
+   ```
+8. Send 5 test bitcoin to RPC CLI wallet.
+   ```
+   bitcoin-cli -rpcwallet="test" -datadir=/tmp/regtest/bitcoind -regtest -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> sendtoaddress <address> 5
+   ```
+9. Sync blockchain with RPC CLI wallet.
+   ```
+   cargo run -- --network regtest sync
+   <CNTRL-C to stop syncing>
+   ```
+10. Get RPC CLI wallet unconfirmed balances.
+   ```
+   cargo run -- --network regtest balance
+   ```
+11. Generate 1 block with reward to test bitcoind wallet address.
+   ```
+   bitcoin-cli -datadir=/tmp/regtest/bitcoind -rpcuser=<your-rpc-username> -rpcpassword=<your-rpc-password> -regtest generatetoaddress 10 $BITCOIND_ADDRESS
+   ```
+12. Sync the blockchain with RPC CLI wallet.
+   ```
+   cargo run -- --network regtest sync
+   <CNTRL-C to stop syncing>
+   ```
+13. Get RPC CLI wallet confirmed balances.
+   ```
+   cargo run -- --network regtest balance
+   ```
+14. Get RPC CLI wallet transactions.
+   ```
+   cargo run -- --network regtest txout list
+   ```