Add config docs for desktop and TUI

[tigerros]

Closes DioxusLabs/dioxus#1474. This adds:

• Links to the tauri-bundler docs.
• Example Dioxus.toml for desktop.

Please take a look at the example Dioxus.toml. I haven't tested it, I just assumed that's what it would look like.

[tigerros]

I'm not sure if this is required with dx bundle. I can't run dx build without the mandatory fields, so I assume it is required.

[tigerros]

Not sure if this is required either. I can't run dx build without the web-specific fields, so I assume it is required.

[ealmloff]

I would like to get this documented without just linking users to the Tauri docs. The Tauri docs are often unclear and since we use a different format it can be confusing to see where we override Tauri.

(I can take over if that is not something you are interested in. I just wanted to give you some information on why this isn't merged yet)

[tigerros]

I would like to get this documented without just linking users to the Tauri docs. The Tauri docs are often unclear and since we use a different format it can be confusing to see where we override Tauri.

Sure, but I don't really know anything about the desktop config, so I'll hand this to someone else. I also just don't like "duplicating" docs, because it makes our docs potentially outdated in the future.

[ealmloff]

I also just don't like "duplicating" docs, because it makes our docs potentially outdated in the future.

We won't get updates as the upstream docs change, but since our tauri-bundle version is pinned to an old version of the library we don't necessarily have the features the new upstream doc updates may talk about.

Right now there will a lot of duplication between the docs, but as Dioxus evolves, our docs will be different anyway. For example, how you tell the bundler what assets to bundle will change with DioxusLabs/dioxus#1369