docs: Add content for mlapi manual.md (#639)

resolves #553
resolves MTT-534

Author: Jesse Olmer

com.unity.multiplayer.mlapi/Documentation~/Manual.md

@@ -1,6 +1,22 @@
-# **Unity MLAPI Manual**
+# About MLAPI
 
+Unity MLAPI is a high level networking library built for the Unity game engine to abstract networking. This allows developers to focus on the game rather than low level protocols and networking frameworks. 
 
-# Getting Started
+##  Unity MLAPI 
 
-Fill this in
+ See this guide to install Unity MLAPI, set up your project, and get started with your first networked game.
+ [First Steps with Unity MLAPI](https://docs-multiplayer.unity3d.com/docs/tutorials/helloworldintro)
+
+# Technical details
+## Requirements
+
+This version of MLAPI is compatible with the following versions of the Unity Editor:
+
+* 2019.4 and later (recommended)
+* Windows, Mac, Linux platforms are supported by MLAPI
+
+## Document revision history
+
+|Date|Reason|
+|---|---|
+|March 10, 2021|Document created. Matches package version 0.1.0|