docs: update documentation to reflect changes from TON to GRAM, including method renaming and new top-up method

docs/getting-started/quickstart.md

@@ -6,21 +6,33 @@ Use this minimal example to verify that your credentials, cookies, and wallet se
 import asyncio
 
 from pyfragment import FragmentClient
+from pyfragment.enums import PaymentMethod
 
 
 async def main() -> None:
     async with FragmentClient(
         seed="word1 word2 ... word24",
-        api_key="YOUR_TONAPI_KEY",
+        api_key="YOUR_API_KEY",  # tonconsole.com (tonapi, default) or t.me/toncenter
         cookies={
             "stel_ssid": "...",
             "stel_dt": "...",
             "stel_token": "...",
             "stel_ton_token": "...",
         },
+        wallet_version="V5R1",   # or "V4R2", "HighloadV2", "HighloadV3R1"
+        api_provider="tonapi",   # or "toncenter"
     ) as client:
         wallet = await client.get_wallet()
-        print(wallet)
+        print(f"GRAM: {wallet.gram_balance} | USDT: {wallet.usdt_balance}")
+
+        recipient = "https://t.me/username"  # also: @username, username
+
+        stars = await client.purchase_stars(recipient, amount=500, payment_method=PaymentMethod.USDT_GRAM)
+        print(f"Sent {stars.amount} Stars to {stars.username} | tx: {stars.transaction_id}")
+
+        premium = await client.purchase_premium(recipient, months=6, payment_method=PaymentMethod.GRAM)
+        print(f"Sent Premium {premium.amount}m to {premium.username} | tx: {premium.transaction_id}")
+
 
 asyncio.run(main())
 ```