Update ALPN instructions.

[deflaux]

No description provided.

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[deflaux]

See googlegenomics/dataflow-java#160 for similar updates for dataflow.

[mbookman]

Can "open for editing" be trimmed from this sentence? It isn't clear to me what it adds.

[mbookman]

On small thing, otherwise LGTM.

[deflaux]

fixed, thanks!