Update all Stellar How-To guides to use RPC instead of Horizon #1529
Description
What problem does your feature solve?
We'd like to encourage use of RPC over Horizon, but all of our intro content is centered around Horizon's API
What would you like to see?
The of the content and tutorials in https://developers.stellar.org/docs/build can all do the same series of steps, but against RPC's API instead of Horizon's.