Add Overview and Installation Instructions to README (#10)

Author: terenceponce

README.md

@@ -3,12 +3,92 @@
 [![ci](https://github.com/terenceponce/diff_check/actions/workflows/ci.yml/badge.svg)](https://github.com/terenceponce/diff_check/actions/workflows/ci.yml)
 [![codecov](https://codecov.io/gh/terenceponce/diff_check/graph/badge.svg?token=F692aysHWW)](https://codecov.io/gh/terenceponce/diff_check)
 
-## Quick Start
+
+## Overview
+
+Diff Check is a command-line tool that compares two files and prints the
+differences between them.
+
+The way this works is that it builds a 2D matrix of the two files by
+computing for the longest subsequence between each files. It then prints
+the differences between the two files by backtracking through the matrix.
+
+The LCS implementation used is based on this Wikipedia article:
+
+https://en.wikipedia.org/wiki/Longest_common_subsequence
+
+## Getting Started
+
+There are 2 ways to use this application.
+
+- Build the app from source
+- Download the executable and run it
+
+I recommend just building the app from source because downloading the
+executable requires you to have Erlang installed anyway.
+
+### Build from Source
+
+First, clone the repo and go to the new directory.
 
 ```
 git clone git@github.com:terenceponce/diff_check.git
 cd diff_check
+```
+
+Next, make sure that you have the correct version Erlang and Elixir installed
+using [asdf](https://asdf-vm.com/).
+
+**NOTE**: If you are using a different version manager for Erlang and Elixir,
+feel free to ignore this step.
+
+```
 asdf install
+```
+
+Next, install the dependencies needed by this repo and compile the executable.
+
+```
 mix deps.get
-mix test
+mix escript.build
 ```
+
+Finally, run the executable.
+
+```
+./diff_check path/to/base/file path/to/comparison/file
+```
+
+If you don't have any files to compare, you can just use the fixtures used in
+the tests.
+
+```
+./diff_check test/support/fixtures/test_response_1.json test/support/fixtures/test_response_2.json
+```
+
+### Download and Run Executable
+
+**NOTE**: As I mentioned above, this step requires your machine to have Erlang
+installed which is why I recommend just building it from source if you're
+already at that point.
+
+First, go to the [Releases Page] and download the file that looks like this.
+
+```
+diff_check-x.x.x
+```
+
+Finally, run the executable.
+
+```
+./diff_check-x-x-x path/to/base/file path/to/comparison/file
+```
+
+If you don't have any files to compare, you can just use the fixtures used in
+the tests.
+
+```
+./diff_check-x-x-x test/support/fixtures/test_response_1.json test/support/fixtures/test_response_2.json
+```
+
+[Releases Page]: https://github.com/terenceponce/diff_check/releases