docs: update terminology from "gas fees" to "transaction fees"

Author: agentfarmx[bot]

docs/diagram.png

@@ -28,7 +28,7 @@ graph TD
 - **Privacy**: Breaks the on-chain link between sender and recipient addresses
 - **Non-custodial**: Users maintain control of their funds at all times
 - **Optimized for Solana**: Designed to be efficient with Solana's compute units
-- **Relayer support**: Allows third-party relayers to pay for gas fees
+- **Relayer support**: Allows third-party relayers to pay for transaction fees
 - **Multiple denominations**: Supports different deposit amounts
 
 ## Documentation Sections

docs/enslookup.png

@@ -129,7 +129,7 @@ Withdrawal successful!
 
 Now that you've completed a basic private transaction, you can explore more advanced features:
 
-1. [Using relayers](advanced/relayers.md) to pay for gas fees
+1. [Using relayers](advanced/relayers.md) to pay for transaction fees
 2. [Multiple denominations](advanced/denominations.md) for different transaction sizes
 3. [Custom Merkle tree heights](advanced/merkle-tree-heights.md) for different security levels