Walkthrough/Setup needed in Readme

Some things you need to do to set this up:
* (Beaker Browser) Seed Ridder
* Then Fork Ridder
* ...
* (Locally) Go to dat://.../reader on your Ridder copy in your Library
* Accept access from whatever feeds you want to browse from your Ridder
* (on Ridder) Go to the Sources tab & add your feeds

Open the README and compare its current setup instructions with the steps in the issue. Document the Beaker Browser seeding and forking flow, local reader navigation, access approval, and adding feeds from the Sources tab; done means a new user can follow the walkthrough from setup to browsing feeds.

Written by the indexing model from the issue text.