Update installation and build instructions

Author: danieldk

README.md

@@ -16,28 +16,42 @@ embeddings as rust2vec:
   * Memory-mapped
   * Quantized
 
-## Building the module
+## Installation
 
-First, you need `pyo3-pack`:
+The finalfusion module is
+[available](https://pypi.org/project/finalfusion/#files) on PyPi for some
+platforms. You can use `pip` to install the module:
+
+~~~shell
+$ pip install --upgrade finalfusion
+~~~
+
+## Building from source
+
+finalfusion can also be built from source. This requires a Rust toolchain
+that is installed through rustup. First, you need `pyo3-pack`:
 
 ~~~shell
 $ cargo install pyo3-pack
 ~~~
 
-Now you can build finalfusion-python in a virtual environment:
+finalfusion currently requires a nightly version of Rust. You can use rustup
+to switch to a nightly build:
 
 ~~~shell
-$ python3 -m venv ff-env
-$ source ff-env/bin/activate
-$ pyo3-pack develop --release
+# Use the nightly toolchain in the current directory.
+$ rustup override set nightly
 ~~~
 
-To build a wheel:
+Now you can build finalfusion-python wheels for Python versions that are
+detected by `pyo3-pack`:
 
 ~~~shell
 $ pyo3-pack build --release
 ~~~
 
+The wheels are then in the `target/wheels` directory.
+
 ## Getting embeddings
 
 rust2vec uses its own embedding format, which supports memory mapping,
@@ -55,10 +69,10 @@ finalfusion embeddings can be loaded as follows:
 
 ~~~python
 import finalfusion
-embeds = finalfusion.Embeddings("/Users/daniel/twe.fifu")
+embeds = finalfusion.Embeddings("myembeddings.fifu")
 
 # Or if you want to memory-map the embedding matrix:
-embeds = finalfusion.Embeddings("/Users/daniel/twe.fifu", mmap=True)
+embeds = finalfusion.Embeddings("myembeddings", mmap=True)
 ~~~
 
 You can then compute an embedding, perform similarity queries, or analogy
@@ -70,6 +84,10 @@ embeds.similarity("Tübingen")
 embeds.analogy("Berlin", "Deutschland", "Amsterdam")
 ~~~
 
+More usage examples can be found in the
+[examples](https://github.com/danieldk/finalfusion-python/tree/master/examples)
+directory.
+
 ## Where to go from here
 
   * [finalfrontier](https://github.com/danieldk/finalfrontier)