Clarify project description (#2166)

* try to make sentences simpler and less confusing

"targeting mobile and embedded device" - it was unclear whatever it referred to Tangram or Tangram ES

* drop mobile device targeting claim

README.md

@@ -4,7 +4,7 @@ Tangram ES
 [![CircleCI](https://circleci.com/gh/tangrams/tangram-es.svg?style=shield)](https://circleci.com/gh/tangrams/tangram-es)
 [![Contributor Covenant](https://img.shields.io/badge/Contributor%20Covenant-v2.0%20adopted-ff69b4.svg)](CODE_OF_CONDUCT.md)
 
-Tangram ES is a C++ library for rendering 2D and 3D maps from vector data using OpenGL ES. It is a counterpart to [Tangram](https://github.com/tangrams/tangram) that targets mobile and embedded devices.
+Tangram ES is a C++ library for rendering 2D and 3D maps from vector data using OpenGL ES. It is a counterpart to [Tangram](https://github.com/tangrams/tangram).
 
 This repository contains both the core rendering library and sample applications that use the library on Android, iOS, Mac OS X, Ubuntu, and Raspberry Pi.