docs: convert readme to standard markdown and improvements

[codayon]

Description

Currently, the README is written in AsciiDoc (.adoc). While it is powerful, I believe a standard Markdown file would be sufficient for a simple README. Using AsciiDoc might also make new contributors hesitant, as the syntax differs from the more common Markdown.

I think, there can also be some structural improvements. For example,

• Moving compiling guide section to OBK manual
• It goes in depth on several different methods of how a user can install OBK on Arch Linux or it's derivatives
• The Features sections can be moved from here to OBK manual and can be replaced with a bit more description
• We can focus on utilizing packhub or maybe the bash (or pwsh?) script for supported devices (until packhub is ready)
• OBK is also going to be released for macOS and Windows, the tone may needs to be improved so that anyone can understand easily

[mominul]

I’m on board with the changes.

Target the develop branch.

[codayon]

Alright, I will open a draft PR with initial commits!