[wg/das] Charter must commit to signaling implementation status in specifications, not only in the charter

[marcoscaceres]

Context: This issue tracks a concern raised in the TAG review of the 2026 DAS WG charter (w3ctag/design-reviews#1187).

The TAG review states (charter-affecting section, verbatim):

"We would like the WG to find a way to signal the expected support level for each specification... At a minimum, each document's support level should be in its SotD section, but ideally the WG would find a way to ensure that developers reading a specification can tell at a glance which kind of document they're reading."

PR #770 adds implementation status text to the charter itself, which is a welcome step. However, the charter currently makes no commitment to reflect that status in the specifications that developers actually read.

The charter should include language along the following lines (proposed in #770 (comment)):

The Working Group will ensure that each specification clearly communicates both its implementation status and its intended trajectory along the W3C Recommendation Track. At a minimum, the Status of This Document section of each specification will describe the current level of implementation support and whether the specification is expected to advance toward widely implemented Recommendation status.

For specifications with limited or single-engine deployment, the Working Group will ensure that the specification clearly signals its role and intended direction — for example, whether it is an experimental abstraction, a transitional design that points developers toward a consensus alternative, or work with limited deployment serving as documentation.

The Working Group will review specifications with limited implementation support at least annually to evaluate their progress, relevance, and intended trajectory, and will document the outcome of those evaluations publicly.

Related: #770, w3ctag/design-reviews#1187