Rename `release` Makefile target to `tag-release`. Make it not requir…

…e being on main,

but check that the current branch is a descendant of the `origin` remote's `main`, i.e.
pushing to `origin main` would be a fast-forward.

Signed-off-by: Daira Emma Hopwood <daira@jacaranda.org>

Regenerate PDFs.

Set change history entry date.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

Regenerate PDFs.

Set Change History entry date.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

Regenerate PDFs.

[protocol spec] Set Change History entry date.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

Regenerate PDFs.

[protocol spec] Set Change History entry date.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

Regenerate PDFs.