Polishing

[Tim-Evans-Seequent]

With these changes landed I'll push everything to the GMG repo.

• Change version to 0.2.0-beta.1 as the Rust public API has changed with the switch to generic Read and Write support.
• Fix images not showing up in the Rust docs, and added them to the C docs.
• Link to the Github pages documentation from the README.
• Fixed links in the Python docs root.

[robbieaverill]

LGTM