Add React Native snippets

snippets/react-native/buy_btc.ts

@@ -0,0 +1,12 @@
+import {
+    buyBitcoin,
+    BuyBitcoinProvider
+} from "@breeztech/react-native-breez-sdk"
+
+const exampleBuyBtc = async () => {
+    // ANCHOR: buy-btc
+    const buyBitcoinResponse = await buyBitcoin({
+        provider: BuyBitcoinProvider.MOONPAY
+    })
+    // ANCHOR_END: buy-btc
+}