PSA: publishing new WD of Quota Management API on April 9

[Arthur Barstow]

Hi All,

A new Working Draft publication of Quota Management API is planned for 
April 9 using the following version as the basis:

  <https://w3c.github.io/quota-api/TR.html>

If anyone has any major concerns about this, please reply right away.

Note this spec is now using Github <https://w3c.github.io/quota-api/>. 
The permissions of the spec's Hg repository will be set to read-only and 
the spec's Bugzilla component will be marked `Historical` and set to 
read-only.

-Thanks, ArtB