docs: sync with docs.polymarket.com - 2026-05-11

New pages:
- docs/builders/fees.md (Builder Fees)
- docs/trading/deposit-wallets.md (Deposit Wallets)

Updated:
- docs/concepts/pusd.md (Polymarket USD)

docs/concepts/pusd.md

@@ -1,7 +1,3 @@
-> ## Documentation Index
-> Fetch the complete documentation index at: https://docs.polymarket.com/llms.txt
-> Use this file to discover all available pages before exploring further.
-
 # Polymarket USD
 
 > pUSD — the collateral token used for all trading on Polymarket
@@ -163,4 +159,4 @@ function unwrap(address _asset, address _to, uint256 _amount) external
   <Card title="Bridge" icon="arrow-right-arrow-left" href="/trading/bridge/deposit">
     Deposit from other chains — auto-wraps to pUSD
   </Card>
-</CardGroup>
+</CardGroup>