Create glossary

[smythp]

Background

As there are a lot of specialized terms used throughout the Sigstore docs, a glossary may be useful, especially for new users.

Work Plan

Hugo has functionality for taxonomies and terms that may be useful for this purpose, but they may be better suited for tagging and categorization. I'll look into the correct Hugo structure, whether it be a data structure or a markup-based structure. I'll also create an initial small glossary with some frequently used terms.

Notes

I tend to try to make display structures simple on sites like this for accessibility and maintainability reasons, but I'll also consider if there are other ways to display glossary info. (Probably not pop-up, hover, or JS-heavy operations).

References #243

[haydentherapper]

One particular term is "bundle" - It's become overloaded in both Sigstore and the SSCI space. Going forward, we want "bundle" to refer to https://github.com/sigstore/protobuf-specs/blob/main/protos/sigstore_bundle.proto - The collection of verification material to verify a single signature. Previous definitions included the output from Rekor or from Cosign. in-toto has its own definition too - https://github.com/in-toto/attestation/blob/main/spec/v1/bundle.md