Updates to standardization requirements for new features

[Martin Thomson]

I've just updated https://wiki.mozilla.org/ExposureGuidelines which outlines our process for shipping web-visible features.

The major new change is around our requirements that web-exposed features be standardized.  A point about identifying a venue for standardization earlier in the process has been added.

The Intent to Prototype template now asks that you identify where the feature will be standardized and to ensure that the standards body is informed.  This is usually as simple as opening an issue or sending an email, following a process appropriate for that standards body.  You can reference an existing discussion if others have already started that conversation.

This comes from some discussions we've had with Google about a few features that had clear venues and good support. Standardization stalled when no action was taken.  The goal is to avoid this in future.

There are also clearer requirements about what we mean when something is standardized, particularly for features we intend to ship.