add ton send-usd example (#514)

Author: cctdaniel

pages/price-feeds/use-real-time-data/ton.mdx

@@ -27,6 +27,29 @@ Install the Pyth TON SDK and other necessary dependencies using npm:
   </Tabs.Tab>
 </Tabs>
 
+## Write Contract Code
+
+The code snippet below provides an example sending a message to the Pyth price feed contract and call the `parse_price_feed_updates` method:
+
+```func copy
+    ;; Create message to Pyth contract according to schema
+    cell msg = begin_cell()
+        .store_uint(0x18, 6)                              ;; nobounce
+        .store_slice(ctx_pyth_address)                    ;; pyth contract address
+        .store_coins(forward_amount)                      ;; forward amount minus fees
+        .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)       ;; default message headers
+        .store_uint(PYTH_OP_PARSE_PRICE_FEED_UPDATES, 32) ;; pyth opcode
+        .store_ref(price_update_data)                     ;; update data
+        .store_ref(price_ids)                             ;; price feed IDs
+        .store_uint(now() - 100, 64)                      ;; min_publish_time
+        .store_uint(now() + 100, 64)                      ;; max_publish_time
+        .store_slice(my_address())                        ;; target address (this contract)
+        .store_ref(custom_payload)                        ;; custom payload with recipient and amount
+        .end_cell();
+
+    send_raw_message(msg, 0);
+```
+
 ## Write Client Code
 
 The following code snippet demonstrates how to fetch price updates, interact with the Pyth contract on TON, and update price feeds:
@@ -109,4 +132,5 @@ You may find these additional resources helpful for developing your TON applicat
 - [Pyth Price Feed IDs](https://pyth.network/developers/price-feed-ids)
 - [Pyth TON Contract](https://github.com/pyth-network/pyth-crosschain/tree/main/target_chains/ton/contracts)
 - [Pyth TON SDK](https://github.com/pyth-network/pyth-crosschain/tree/main/target_chains/ton/sdk)
-- [Pyth TON Example](https://github.com/pyth-network/pyth-examples/tree/main/price_feeds/ton/sdk_js_usage)
+- [Pyth TON SDK Example](https://github.com/pyth-network/pyth-examples/tree/main/price_feeds/ton/sdk_js_usage)
+- [Pyth TON Send USD Example](https://github.com/pyth-network/pyth-examples/tree/main/price_feeds/ton/send_usd)