Lots of smaller docs improvements ("catch all" docs ticket)

[janpaul123]

Let's put a grab bag of small improvements here as we come across them (but bigger than "lets just fix this right away as we encounter them). Can split into separate tickets if some of these turn out too big.

• Split Rendering 3D Meshes into multiple pages + make clear that this is a full "incrementally port JS to Rust" example
• Add clearer information on what the stability of things is, and what we're focusing on (e.g. version numbers / labels).
• General copyediting (make sure spelling and grammar is correct).
• More information about our history / vision / etc.
• More information about who this is for (both right now and at different stages in the future).
• Info about headers for getting SharedArrayBuffer to work.

[janpaul123]

@stevekrouse notes from this morning:

• Support Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy on dev server vitejs/vite#3909 (comment)

• deafultStyles: false

• ^ example of how to actually call the initialize function

• Explain #repr(C)

• Explain how to have a top level carogo file (for rust analyzer vscode) but set the dist build directory somewhere else

• cargo watch -- cargo zaplib build

• Explain how to use serde to send over json, including using derive feature in cargo.toml