Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2021-08-05' into staging

QAPI patches patches for 2021-08-05

# gpg: Signature made Thu 05 Aug 2021 15:06:12 BST
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-qapi-2021-08-05:
  docs: convert writing-qmp-commands.txt to writing-qmp-commands.rst
  docs/qapi-code-gen: add cross-references
  docs/qapi-code-gen: Beautify formatting
  docs: convert qapi-code-gen.txt to ReST
  docs/devel/qapi-code-gen: Update examples to match current code

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>