Add go/whitelabel

[Hixie]

Adding a design doc.

Presubmit checklist

• This PR doesn’t contain automatically generated corrections (Grammarly or similar).
• This PR follows the Google Developer Documentation Style Guidelines — for example, it doesn’t use i.e. or e.g., and it avoids I and we (first person).
• This PR uses semantic line breaks of 80 characters or fewer.

[khanhnwin]

Thanks @Hixie!

[sfshaza2]

Actually, I don't approve this. Can we revert it? The term "white label" has racist origins and we should NOT use it. https://developers.google.com/style/word-list#white-label

[sfshaza2]

cc @domesticmouse cc @khanhnwin

I went through this recently with Zoey who was using the term in her News blog post. After I pointed it out, she reworded it.

[domesticmouse]

@Hixie please revert. See @sfshaza2 for reasoning

[Hixie]

Looks like it's not so much that it has racist origins (looks like the origin is DJs ripping off the labels from vinyl disks), as much as people have been assigning it racial overtones by virtue of overzealously including it in lists of racial terms, but the effect is much the same in the end...