Remarks on `<hand>` are contradictory

[ahankinson]

As noted in a Slack conversation, the Remarks section of <hand> and the documentation for @initial are not aligned. The remarks say (emphasis mine):

The @initial attribute indicates whether this is the first or main hand of the document.

While the documentation for @initial says:

Marks this hand as the first one of the document.

The discussion on Slack (with @pe-ro and @maxrothman) indicated that using @initial for the main hand of the document was insufficient, and an alternate solution should be found, possibly borrowing TEI's @scope from <handNote> (https://tei-c.org/release/doc/tei-p5-doc/en/html/ref-att.handFeatures.html)

In any case, the remarks and the description should be aligned, so a PR is incoming to remove the conflict. A separate issue will also be created for @scope.