Incorporate Bert Tenjy's Vector ABI (libmvec) into ELF v2 document

[openpower-gitea-migrator]

Originally Gitea issue #101 by @toshywoshy on 2020-02-21

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The vector ABI is located here: https://github.com/power8-abi-doc/vector-function-abi

[openpower-gitea-migrator]

@toshywoshy commented on 2020-05-04

It's uncertain whether this will be stable enough in time for the release, but we can make a decision as we get closer to publication.