qapi: new doc comment "Intro" section
This patch adds an "Intro" doc section, intended to eventually replace the "Plain" doc section alongside a forthcoming "Details" section. For now, this section is not actually instantiated or used, but subsequent patches will slowly convert the leading introductory sections of QAPIDoc documentation to use this new section. A main motivation of this series of changes is to more explicitly delineate the "Introductory" documentation for each QAPI definition for the sake of the inliner. When inlining members, examples, and details from multiple QAPIDoc sections, we will want to omit the "Introductory" text from inlined definitions while keeping notes, caution boxes, examples, and so on. This new section facilitates that. Signed-off-by: John Snow <jsnow@redhat.com> Message-ID: <20260611042332.482979-8-jsnow@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> [Commit message tweaked] Signed-off-by: Markus Armbruster <armbru@redhat.com>