Add build and usage instructions to the README.

Author: danieldk

README.md

@@ -7,6 +7,47 @@ finalfrontier-python is a Python module for
 finalfrontier-python is still under development, precompiled modules will be
 made available in the future.
 
+## Building the module
+
+First, you need `pyo3-pack`:
+
+~~~shell
+$ cargo install pyo3-pack
+~~~
+
+Now you can build finalfrontier-python in a virtual environment:
+
+~~~shell
+$ python3 -m venv ff-env
+$ source ff-env/bin/activate
+$ pyo3-pack develop --release
+~~~
+
+To build a wheel:
+
+~~~shell
+$ pyo3-pack build --release
+~~~
+
+## Usage
+
+A finalfrontier model can be loaded as follows:
+
+~~~python
+import finalfrontier
+model = finalfrontier.Model("/Users/daniel/git/finalfrontier/throwaway.bin")
+~~~
+
+You can then compute an embedding, perform similarity queries, or analogy
+queries:
+
+~~~python
+e = model.embedding("Tübingen")
+model.similarity("Tübingen")
+model.analogy("Berlin", "Deutschland", "Amsterdam")
+~~~
+
+
 ## Where to go from here
 
   * [finalfrontier](https://git.danieldk.eu/finalfrontier/about)