chore: made Cargo.toml and readme less CLI-centric

[Enyium]

As touched on in #142.

Regarding Cargo.toml changes to categories

See also:

• https://crates.io/category_slugs
• https://crates.io/categories

The category "command-line-interface" IMO doesn't fit ("Crates to help create command line interfaces, such as argument parsers, line-editing, or output coloring and formatting"), just like "gui" doesn't fit ("Crates to help you create a graphical user interface").

When you read the description for the category "web-programming" - "Crates to create applications for the web" - you may also think that it doesn't fit. But look at the descriptions of the subcategories:

web-programming::http-client
    Crates to make HTTP network requests.

web-programming::http-server
    Crates to serve data over HTTP.

web-programming::websocket
    Crates to communicate over the WebSocket protocol.

These subcategories put "web-programming" in the light of "Crates to create applications augmented with web functionality". And this fits perfectly.

Other

✔ Checklist:

• Commit messages have been written in Conventional Commits format;
• Not applicable: [ ] Tests for the changes have been added (for bug fixes / features).

[mgrachev]

@Enyium Thank you!

Please fix all linter's suggestions 🙏