Update README

cadquery/README.md

@@ -9,7 +9,28 @@
 - [main repo](https://github.com/CadQuery/cadquery)
 - [GUI repo](https://github.com/CadQuery/CQ-editor)
 
-## Standalone
+## About
+
+CADQuery is a Python library for doing CAD with code. In this regard it follows in the footsteps of
+[OpenSCAD](https://openscad.org/). However CADQuery has a higher level API that allows you to write
+scripts that look more like reasonable verbal descriptions of the part (or at least what you'd do to
+make it in a standard CAD program). In particular, it's easy to define new workplanes, make 2D
+sketches in them, and extrude, as one would in standard CAD. CADQuery also has support for common
+operations like filleting, chamfers, and hollowing (making shells). And it supports constraints!
+
+CADQuery started as a wrapper around the [FreeCAD](https://www.freecadweb.org/) API. But now it's
+built on top of the underlying [Open CASCADE
+kernel](https://www.opencascade.com/open-cascade-technology/) directly so that it can support some
+more advanced geometric selection and editing.
+
+Most importantly, CADQuery functions as a Python library, so you can write Python scripts that
+generate geometry and export it (as STL, STEP, etc.). There's also a dedicated GUI that shows your
+code in one pane, and the constructed part in another (along with a console and some debugging
+info).
+
+## Installation
+
+### Standalone
 
 The instructions here are based off of [this video](https://www.youtube.com/watch?v=sjLTePOq8bQ).
 
@@ -48,12 +69,12 @@ Type "help", "copyright", "credits" or "license" for more information.
 <cadquery.cq.Workplane object at 0x7fd6a24b21d0>
 ```
 
-## GUI
+### GUI
 
 There are several ways to install the CADQuery GUI. Their website recommends using an installer
 script, but I would recommend using Miniconda as we did for the standalone version.
 
-### Miniconda
+#### Miniconda
 
 First, clone the [CADQuery Editor repo](https://github.com/CadQuery/CQ-editor). From within that
 project, run `conda env create -f cqgui_env.yml -n cqgui`, followed by `conda activate cqgui`. You
@@ -63,7 +84,7 @@ Note: In theory, you can also install the GUI without cloning any repos by makin
 environment (e.g. `conda create -n cqgui`), activating it (`conda activate cqgui`), and running
 `conda install -c cadquery -c conda-forge cq-editor=master`. But this didn't work for me.
 
-### Installer Script
+#### Installer Script
 
 The easiest way to install the GUI is to download and extract the [zipped
 release](https://github.com/CadQuery/CQ-editor/releases) for your system. It contains a script