chore: Update example links in README

Author: Randy808

README.md

@@ -61,10 +61,10 @@ that the `Wallet` can use to update its view of the chain.
 
 **Examples**
 
-* [`examples/esplora_async`](https://github.com/bitcoindevkit/bdk_wallet/tree/master/examples/esplora_async)
-* [`examples/esplora_blocking`](https://github.com/bitcoindevkit/bdk_wallet/tree/master/examples/esplora_blocking)
-* [`examples/electrum`](https://github.com/bitcoindevkit/bdk_wallet/tree/master/examples/electrum)
-* [`examples/bitcoind_rpc`](https://github.com/bitcoindevkit/bdk_wallet/tree/master/examples/bitcoind_rpc)
+* [`examples/esplora_async`](https://github.com/bitcoindevkit/bdk_wallet/blob/master/examples/esplora_async.rs)
+* [`examples/esplora_blocking`](https://github.com/bitcoindevkit/bdk_wallet/blob/master/examples/esplora_blocking.rs)
+* [`examples/electrum`](https://github.com/bitcoindevkit/bdk_wallet/blob/master/examples/electrum.rs)
+* [`examples/bitcoind_rpc`](https://github.com/bitcoindevkit/bdk_wallet/blob/master/examples/bitcoind_rpc.rs)
 
 ## Persistence