Cherry-pick to master: Add 7.7.1 relnotes (#21937)#21941

Merged

dedemorton merged 1 commit intoelastic:masterfrom dedemorton:backport/master/pr-21937

Oct 16, 2020

+39-1

Commits on Oct 16, 2020

Add 7.7.1 relnotes to 7.8 docs (elastic#21937 )

dedemorton
and
gbanasiak
committed