docs: update README with goal (#78)

README.md

@@ -1,5 +1,23 @@
 # Bazel rules for Unreal Engine
 
+## Goal
+
+The goal of this project is to provide a set of Bazel rules to build Unreal Engine itself and Unreal Engine projects with Bazel.
+
+### Motivation
+
+I'm making my own game using Unreal. I have a background in Software Engineering/Ops and I found it difficult to navigate all the custom build scripts and tools that Unreal Engine uses.
+I want it to be easier to build Unreal Engine and Unreal Engine projects in different environments (Linux, Windows, Mac, CI/CD, etc) without having to think about the ins
+and outs of Unreal Engine's build system.
+
+### Why Bazel?
+
+[Bazel](https://bazel.build) is a build system that is designed to be fast, reliable, and reproducible. I know it well enough to be able to map Unreal Engine's build system to it.
+
+### Why not use Unreal's build system?
+
+Unreal Engine's build system is complex and not well documented (in my opinion). It's difficult to understand how to build Unreal Engine and Unreal Engine projects in different environments.
+
 ## Quick start
 
 TODO
@@ -10,8 +28,10 @@ TODO
   - [ ] Download a specific commit of Unreal Engine as a bazel repo rule
   - [ ] Configure Unreal Engine (mimic `Setup.(bat|sh)` functionality)
     - [ ] Download git dependencies
+    - [ ] Unpack git dependencies
   - [ ] Build a module of Unreal Engine in Bazel
     - [ ] Build an Unreal module with no dependencies
     - [ ] Link Unreal Engine modules together
+  - [ ] Build Unreal Editor in Bazel
 - [ ] Build and Package Unreal Engine projects in Bazel
   - [ ] Generate BUILD files for Unreal Engine plugins