docs: update 3.4 references to 3.5
Created by: ggilmore
cc @sourcegraph/distribution
@christinaforney @ryan-blunden please merge this PR when you are ready to announce 3.5.0's release.
Created by: ggilmore
cc @sourcegraph/distribution
@christinaforney @ryan-blunden please merge this PR when you are ready to announce 3.5.0's release.