add Quicknode x402 section to data fetching guide

[Sahilsen]

What changed? Why?

• Added a Quicknode section in the guide, which allows agents to pay-per-request for RPC calls even without authenticating

Notes to reviewers

How has it been tested?

• Yes, tested the build locally

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[cb-heimdall]

Review Error for luccastera @ 2026-04-03 15:32:28 UTC
User failed mfa authentication, see go/mfa-help