Docs: Custom root page instructions shouldn't depend on Oasis

[ocdtrekkie]

When creating your own page like this, we suggest using the Oasis splash URL as a starting point. Use your browser's DOM inspector to find the IFRAME that is on the background of Oasis. Use its CSS rules to guide your own.

Which is in https://docs.sandstorm.io/en/latest/administering/faq/

This is no longer a particularly useful instruction. Perhaps if Kenton could pull that grain onto Alpha and link it;s public URL, or give Alpha a similar custom splash for people to use as a reference?

[kentonv]

Here's a backup of the splash page grain:

Oasis Splash.zip