Create documentation for Quicknode provider feature

[mconnelly8]

• Update docs : QuickNodes is now default provider.
• Update docs : there is rate limit of QuickNode provider & create new user account in case of limit reached by using web3.js referral link for supporting web3.js lib
• Adding External providers guide:
  how to create instance of Quicknode provider and use with web3 for custom Network, Transport and token , example code is

  web3.js/packages/web3/test/integration/web3RPCProviders.test.ts

  Line 32 in bfe2769

  const provider = new QuickNodeProvider(network, transport);

[jdevcs]

Documentation of Quicknode rate limit