Add a bit more documentation to the README

README.md

@@ -3,7 +3,17 @@ Scanning Tunneling Microscope
 This repository contains the technical documents for the [Scanning Tunneling
 Microscope (STM) we are currently (re)building](https://wiki.fa-fo.de/projects:stm).
 
-The whole document is currently work in progress.
+### State of the project
+Our STM build is currently work in progress and we have not yet achieved
+imaging.  Please check our [lab notes](https://wiki.fa-fo.de/projects:stm:log)
+for current updates.
 
 ### Working State of the CAD Model
 ![CAD Screenshot](./CAD-Screenshot.png)
+
+### Directory Structure
+- [`Electronics/`](./Electronics) — Schematics of the STM control box and preamplifier
+- [`Drawings/`](./Drawings) — Mechanical drawings for various parts (mostly the vibration isolation frame)
+- [`Mechanical/`](./Mechanical) — CAD model (FreeCAD)
+- [`Control/`](./Control) — Software for controlling the STM
+- [`Calculations/`](./Calculations) — Jupyter notebooks for various calculations around the STM