update README with reference to cli project

Author: tyler-gilbert

README.md

@@ -1,7 +1,5 @@
 # API
 
-![Build](https://github.com/StratifyLabs/API/workflows/Build/badge.svg)
-
 ## Overview
 
 API is a collection of cross-platform C++ libraries for 
@@ -21,6 +19,13 @@ including
 - [ThreadAPI](libraries/ThreadAPI): thread management
 - [VarAPI](libraries/VarAPI): data and strings
 
+## How to Build
+
+The `API` library is designed to be a CMake sub-project. To build, please use one of these projects:
+
+- Desktop [Command Line Interface](https://github.com/StratifyLabs/cli)
+- [Stratify OS on Nucleo-144](https://github.com/StratifyLabs/StratifyOS-Nucleo144)
+
 ## Design
 
 The API framework is a hard to mis-use, non-onerous C++ API achieved using the following principles: