Typos, minor additions

[qmonnet]

Hi Jesper, and thanks for this doc it will be super useful!

Here is a small PR with:

• typo fixes,
• clang/LLVM version number for bcc,
• additional areas in which eBPF can be used.

These are suggestions, of course feel free to reject any of this if you did not plan to add it that way.

For future edits, could you please precise what's the text width you are using for text wrapping?