qapi: @foo should be used to reference, not `foo`

Documentation suggests @foo is merely shorthand for ``foo``.  It's
not, it carries additional meaning: it's a reference to a QAPI schema
name.

Reword the documentation to spell that out.

Fix up the few ``foo`` that should be @foo.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20230425064223.820979-7-armbru@redhat.com>

docs/devel/qapi-code-gen.rst

@@ -924,9 +924,11 @@ first character of the first line.
 
 The usual ****strong****, *\*emphasized\** and ````literal```` markup
 should be used.  If you need a single literal ``*``, you will need to
-backslash-escape it.  As an extension beyond the usual rST syntax, you
-can also use ``@foo`` to reference a name in the schema; this is rendered
-the same way as ````foo````.
+backslash-escape it.
+
+Use ``@foo`` to reference a name in the schema.  This is an rST
+extension.  It is rendered the same way as ````foo````, but carries
+additional meaning.
 
 Example::
 

docs/interop/firmware.json

@@ -258,7 +258,7 @@
 #
 # @mode: Describes how the firmware build handles code versus variable
 #        storage. If not present, it must be treated as if it was
-#        configured with value ``split``. Since: 7.0.0
+#        configured with value @split. Since: 7.0.0
 #
 # @executable: Identifies the firmware executable. The @mode
 #              indicates whether there will be an associated
@@ -267,13 +267,13 @@
 #                  -drive if=none,id=pflash0,readonly=on,file=@executable.@filename,format=@executable.@format
 #                  -machine pflash0=pflash0
 #              or equivalent -blockdev instead of -drive. When
-#              @mode is ``combined`` the executable must be
+#              @mode is @combined the executable must be
 #              cloned before use and configured with readonly=off.
 #              With QEMU versions older than 4.0, you have to use
 #                  -drive if=pflash,unit=0,readonly=on,file=@executable.@filename,format=@executable.@format
 #
 # @nvram-template: Identifies the NVRAM template compatible with
-#                  @executable, when @mode is set to ``split``,
+#                  @executable, when @mode is set to @split,
 #                  otherwise it should not be present.
 #                  Management software instantiates an
 #                  individual copy -- a specific NVRAM file -- from

qapi/qom.json

@@ -637,7 +637,7 @@
 #
 # @discard-data: if true, the file contents can be destroyed when QEMU exits,
 #                to avoid unnecessarily flushing data to the backing file. Note
-#                that ``discard-data`` is only an optimization, and QEMU might
+#                that @discard-data is only an optimization, and QEMU might
 #                not discard file contents if it aborts unexpectedly or is
 #                terminated using SIGKILL. (default: false)
 #

qapi/ui.json

@@ -1247,7 +1247,7 @@
 #              available node on the host.
 #
 # @p2p: Whether to use peer-to-peer connections (accepted through
-#       ``add_client``).
+#       @add_client).
 #
 # @audiodev: Use the specified DBus audiodev to export audio.
 #