Move Alexey to CREDITS.

I am probably not giving him enough justice with
the description line..

Subsystem NETWORKING [IPv4/IPv6]
  Changes 1535 / 5111 (30%)
  Last activity: 2020-12-10
  "David S. Miller" <[email protected]>:
    Author b7e4ba9a 2020-12-09 00:00:00 407
    Committer e0fecb28 2020-12-10 00:00:00 3992
    Tags e0fecb28 2020-12-10 00:00:00 3978
  Alexey Kuznetsov <[email protected]>:
  Hideaki YOSHIFUJI <[email protected]>:
    Tags d5d8760b 2016-06-16 00:00:00 8
  Top reviewers:
    [225]: [email protected]
    [222]: [email protected]
    [176]: [email protected]
  INACTIVE MAINTAINER Alexey Kuznetsov <[email protected]>

Signed-off-by: Jakub Kicinski <[email protected]>