add context to quickstart guide

[wolovim]

What was wrong?

Nothing egregious, but thought we could slow down and connect a couple more dots in the quickstart section.

How was it fixed?

• Added more explicit Provider descriptions with example guides for local Geth nodes and Infura providers.
  • The existing Infura guide was augmented a bit, but my assumption is that the other most popular use case worth addressing is the local Geth node scenario (whether in --dev mode or not). Trinity Soon™ 🤞
  • The local node case also feels prudent for encouraging decentralization. Don't think it makes sense to discuss that philosophically in a quickstart guide, however.
• Removed a couple small things that felt out of the scope of a quickstart guide.

Preview link: https://web3py--1673.org.readthedocs.build/en/1673/quickstart.html

Todo:

• Add entry to the release notes

Cute Animal Picture

[cburgdorf]

Looks like a nice overhaul 👍