Update readme

Expanded readme to include a demo, a "how it works" section, and a general
overview of Farside's purpose.

README.md

@@ -1,12 +1,67 @@
 ![Farside](img/farside.svg)
 
-___
-
+[![Latest Release](https://img.shields.io/github/v/release/benbusby/farside?label=Release)](https://github.com/benbusby/farside/releases)
+[![MIT License](https://img.shields.io/github/license/benbusby/earthbound-themes.svg)](http://opensource.org/licenses/MIT)
 [![Elixir CI](https://github.com/benbusby/privacy-revolver/actions/workflows/elixir.yml/badge.svg)](https://github.com/benbusby/privacy-revolver/actions/workflows/elixir.yml)
 
-A redirecting service for FOSS alternative frontends
+A redirecting service for FOSS alternative frontends.
 
-### Development
+[Farside](https://farside.link) provides links that automatically redirect to
+working instances of privacy-oriented alternative frontends, such as Nitter,
+Libreddit, etc. This allows for users to have more reliable access to the
+available public instances for a particular service, while also helping to
+distribute traffic more evenly across all instances and avoid performance
+bottlenecks and rate-limiting.
+
+## Demo
+
+| Service | Page | Farside Link |
+| -- | -- | -- |
+| [Libreddit](https://github.com/spikecodes/libreddit) | /r/popular | https://farside.link/libreddit/r/popular
+| [Nitter](https://github.com/zedeus/nitter) | User Profile | https://farside.link/nitter/josevalim
+| [Invidious](https://github.com/iv-org/invidious) | Home Page | https://farside.link/invidious
+| [Bibliogram](https://sr.ht/~cadence/bibliogram/) | User Profile | https://farside.link/bibliogram/u/kbdfans
+
+## How It Works
+
+The app runs in a container that periodically (default every 5 minutes) queries
+all instances for services defined in [services.json](services.json). For each
+instance, as long as the instance takes <5 seconds to respond and returns a 200
+status code, the instance is added to a list of available instances for that
+particular service. If not, it is discarded until the next update period. 
+
+Farside's routing is very minimal, with only the following routes:
+
+- `/`
+  - The app home page, displaying all live instances for every service
+- `/ping`
+  - A passthrough "ping" to redis to ensure both app and redis are working
+- `/:service/*glob`
+  - The main endpoint for redirecting a user to a working instance of a
+    particular service with the specified path
+  - Ex: `/libreddit/r/popular` would navigate to `<libreddit instance
+    URL>/r/popular`
+  - Note that a path is not required. `/libreddit` for example will still
+    redirect the user to a working libreddit instance
+
+When a service is requested with the `/:service/...` endpoint, Farside requests
+the list of working instances from Redis and returns a random one from the list
+and adds that instance as a new entry in Redis to remove from subsequent
+requests for that service. For example:
+
+A user navigates to `/nitter` and is redirected to `nitter.net`. The next user
+to request `/nitter` will be guaranteed to not be directed to `nitter.net`, and
+will instead be redirected to a separate (random) working instance. That
+instance will now take the place of `nitter.net` as the "reserved" instance, and
+`nitter.net` will be returned to the list of available Nitter instances. 
+
+This "reserving" of previously chosen instances is performed in an attempt to
+ensure better distribution of traffic to available instances for each service.
+
+Farside also has built-in IP ratelimiting for all requests, enforcing only one
+request per second per IP.
+
+## Development
 
 - Install [redis](https://redis.io)
 - Install [elixir](https://elixir-lang.org/install.html)
@@ -15,3 +70,4 @@ A redirecting service for FOSS alternative frontends
 - Initialize redis contents: `mix run update.exs`
 - Run Farside: `mix run --no-halt`
   - Uses localhost:4001
+