docs: Extend documentation

[niclashedam]

We need a few more documentation entries in the docs folder.
I think these would make good sense:

• What is eBPF?
• How are eBPF programs loaded? Should describe the loading and attachment functions used in this project.
• Architecture of eBPF Should describe how tracepoints work and how to find information about specific tracepoints.
• Limitations Should describe the limitations of eBPF programs.