Documentation: root permission/access requirements in bcc/docs/kernel-versions.md

Despite the fact, that major Linux distributions set either `kernel.unprivileged_bpf_disabled = 0` (or give capability `CAP_BPF` to all processes of all users) *by default*, I think it'd be valuable to add information about (potentially) required `root` permissions/access to the documentation (incl. note about `kernel.unprivileged_bpf_disabled = 0` and `CAP_BPF`).

Namely to the table **Program Types** in `bcc/docs/kernel-versions.md`. Maybe as another column before the current first column `Program Type`.

Open bcc/docs/kernel-versions.md and read the Program Types table, then verify how root access, kernel.unprivileged_bpf_disabled, and CAP_BPF affect the documented program types. Done means the table clearly includes the potentially required access information without obscuring its existing kernel-version guidance.

Written by the indexing model from the issue text.