qapi: Fix bullet list markup in documentation

Peter Maydell's commit 100cc4fe0f explains:

    rST insists on a blank line before and after a bulleted list [...]
    Add some extra blank lines in the doc comments so they're
    acceptable rST input.

It missed one in qapi/trace.json.

Paolo Bonzini later added another instance in qapi/stats.json,
providing further, if unintended, evidence for his quip that rST is
the Perl of ASCII-based markups.

Both are parsed as ordinary paragraph, resulting in garbled output.

John Snow missed the need for a blank line when converting
docs/devel/qapi-code-gen.txt to rST.

Add the blank lines we need to get the bullet lists recognized as
such.

Kevin Wolf and Lukas Straub added two more, but indented.  Sphinx
recognizes them as (indented) bullet lists.  The indentation looks
slightly off.

Insert a blank line and delete the extra indentation.

Fixes: 100cc4fe0f (qapi: Add blank lines before bulleted lists)
Fixes: 467ef823d8 (qmp: add filtering of statistics by target vCPU)
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: <20230425064223.820979-10-armbru@redhat.com>
[Fix of docs/devel/qapi-code-gen.rst squashed, commit message adjusted]

docs/devel/qapi-code-gen.rst

@@ -934,6 +934,7 @@ Example::
 
  ##
  # Some text foo with **bold** and *emphasis*
+ #
  # 1. with a list
  # 2. like that
  #

qapi/block-export.json

@@ -275,9 +275,10 @@
 # @deprecated: This command is deprecated. Use @block-export-del instead.
 #
 # Returns: error if
-#            - the server is not running
-#            - export is not found
-#            - mode is 'safe' and there are existing connections
+#
+#          - the server is not running
+#          - export is not found
+#          - mode is 'safe' and there are existing connections
 #
 # Since: 2.12
 ##

qapi/stats.json

@@ -107,6 +107,7 @@
 # The arguments to the query-stats command; specifies a target for which to
 # request statistics and optionally the required subset of information for
 # that target:
+#
 # - which vCPUs to request statistics for
 # - which providers to request statistics from
 # - which named values to return within each provider

qapi/trace.json

@@ -87,6 +87,7 @@
 # @vcpu: The vCPU to act upon (all by default; since 2.7).
 #
 # An event's state is modified if:
+#
 # - its name matches the @name pattern, and
 # - if @vcpu is given, the event has the "vcpu" property.
 #

qapi/yank.json

@@ -50,16 +50,17 @@
 # hanging QEMU.
 #
 # Currently implemented yank instances:
-#  - nbd block device:
-#    Yanking it will shut down the connection to the nbd server without
-#    attempting to reconnect.
-#  - socket chardev:
-#    Yanking it will shut down the connected socket.
-#  - migration:
-#    Yanking it will shut down all migration connections. Unlike
-#    @migrate_cancel, it will not notify the migration process, so migration
-#    will go into @failed state, instead of @cancelled state. @yank should be
-#    used to recover from hangs.
+#
+# - nbd block device:
+#   Yanking it will shut down the connection to the nbd server without
+#   attempting to reconnect.
+# - socket chardev:
+#   Yanking it will shut down the connected socket.
+# - migration:
+#   Yanking it will shut down all migration connections. Unlike
+#   @migrate_cancel, it will not notify the migration process, so migration
+#   will go into @failed state, instead of @cancelled state. @yank should be
+#   used to recover from hangs.
 #
 # Since: 6.0
 ##