qapi: Add blank lines before bulleted lists

We would like to switch the doc comments to rST format. rST
insists on a blank line before and after a bulleted list, but our
Texinfo doc generator did not. Add some extra blank lines in the doc
comments so they're acceptable rST input.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200213175647.17628-17-peter.maydell@linaro.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

qapi/block-core.json

@@ -4757,6 +4757,7 @@
 #
 # Once the tray opens, a DEVICE_TRAY_MOVED event is emitted. There are cases in
 # which no such event will be generated, these include:
+#
 # - if the guest has locked the tray, @force is false and the guest does not
 #   respond to the eject request
 # - if the BlockBackend denoted by @device does not have a guest device attached

qapi/char.json

@@ -133,6 +133,7 @@
 # @data: data to write
 #
 # @format: data encoding (default 'utf8').
+#
 #          - base64: data must be base64 encoded text.  Its binary
 #            decoding gets written.
 #          - utf8: data's UTF-8 encoding is written
@@ -167,6 +168,7 @@
 # @size: how many bytes to read at most
 #
 # @format: data encoding (default 'utf8').
+#
 #          - base64: the data read is returned in base64 encoding.
 #          - utf8: the data read is interpreted as UTF-8.
 #            Bug: can screw up when the buffer contains invalid UTF-8

qapi/trace.json

@@ -53,6 +53,7 @@
 # Returns: a list of @TraceEventInfo for the matching events
 #
 #          An event is returned if:
+#
 #          - its name matches the @name pattern, and
 #          - if @vcpu is given, the event has the "vcpu" property.
 #

qapi/ui.json

@@ -934,6 +934,7 @@
 # Input event union.
 #
 # @type: the input type, one of:
+#
 #        - 'key': Input event of Keyboard
 #        - 'btn': Input event of pointer buttons
 #        - 'rel': Input event of relative pointer motion