Merge branch 'bpf-doc-improvements'

Andrii Nakryiko says:

====================
A bunch of BPF-related docs typo, wording and formatting fixes.

v1->v2:
- split off non-documentation changes into separate patchset
====================

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>