bpf, docs: Add myself to BPF docs MAINTAINERS entry

bpf, docs: Add myself to BPF docs MAINTAINERS entry

In commit 7e2a9ebe8126 ("docs, bpf: Ensure IETF's BPF mailing list gets
copied for ISA doc changes"), a new MAINTAINERS entry was added for any
BPF IETF documentation updates for the ongoing standardization process.
I've been making it a point to try and review as many BPF documentation
patches as possible, and have made a committment to Alexei to
consistently review BPF standardization patches going forward. This
patch adds my name as a reviewer to the MAINTAINERS entry for the
standardization effort.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230214223553.78353-1-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>