docs: overhaul documentation

The documentation is probably the single most important part of this project at the moment and its not in a good state. Going forward I want to focus much more on it with a couple goals: 1. make it MUCH easier for potentially interested ppl to contribute. This means explaining wth is going on, where to find stuff, how stuff fits together. 2. document the current behavior and already existing features (esp the more hidden kernel features such as debugging flags etc) A rough structure for the docs: ``` ├── Introduction │ - What is k23? │ - Core Concepts? │ - Roadmap │ ├── For App Developers │ - (how to deploy an application on k23, this will be a stub for now) │ ├── Hacking on k23 │ - Welcome │ - Ways to Contribute │ - Community & Getting Help │ │ │ ├── Getting Started │ │ - Prerequisites & Setup │ │ - Building & Running │ │ - Running the Tests │ │ - Debugging │ │ - Your First PR │ │ │ ├── Architecture │ │ ├── Codebase Tour │ │ ├── How the Boot Process Works │ │ ├── How the WASM Runtime Works │ │ ├── How Memory Management Works │ │ └── How Traps & Syscalls Work │ │ │ └── How-To Guides │ ├── Adding a WASM Feature │ └── Adding a Syscall │ ├── Reference │ ├── ASLR │ ├── Memory Layout │ ├── WASM Feature Status │ ├── WASI API Status │ ├── Boot Arguments │ ├── CPU Architectures │ │ │ │ │ ├── RISC-V │ │ ├── AArch64 │ │ └── x86_64 │ └── Glossary │ └── Code of Conduct ```