This brings our code of conduct and security file in line with automated
checks.
The changes to `SECURITY.md` are mostly formatting, adding newlines so
it line wraps at 80 lines and fixing a dead link.
The `CODE_OF_CONDUCT.md` is a more substantial change. Rather than the
being subject to both the contributor covenant and the Hyperledger CoC
this change makes the project only subject to the Hyperledger CoC.
Signed-off-by: Danno Ferrin <danno.ferrin@gmail.com>