Demos should reflect name change from 'Feature Policy' to 'Permissions Policy'

[jpmedley]

https://www.chromestatus.com/features/5745992911552512
https://w3c.github.io/webappsec-permissions-policy/

[jpchase]

The source for demos have already been updated to reflect the rename/split to Permissions Policy and Document Policy (e.g. #30, #31). We do need to deploy the changes to the running site - lost track of that.

[jpchase]

We've finally deployed the changes, so the current version of the site reflects the appropriate naming. Feel free to reopen if you notice any references to the old naming.

[jpmedley]

Thanks!