qmp-commands: move 'blockdev-add' doc to schema

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

qapi/block-core.json

@@ -2830,6 +2830,45 @@
 # to help with its development.
 #
 # Since: 1.7
+#
+# Example:
+#
+# 1.
+# -> { "execute": "blockdev-add",
+#      "arguments": {
+#          "options" : { "driver": "qcow2",
+#                        "file": { "driver": "file",
+#                                  "filename": "test.qcow2" } } } }
+# <- { "return": {} }
+#
+# 2.
+# -> { "execute": "blockdev-add",
+#      "arguments": {
+#          "options": {
+#            "driver": "qcow2",
+#            "node-name": "node0",
+#            "discard": "unmap",
+#            "cache": {
+#                "direct": true,
+#                "writeback": true
+#            },
+#            "file": {
+#                "driver": "file",
+#                "filename": "/tmp/test.qcow2"
+#            },
+#            "backing": {
+#                "driver": "raw",
+#                "file": {
+#                    "driver": "file",
+#                    "filename": "/dev/fdset/4"
+#                }
+#            }
+#          }
+#        }
+#      }
+#
+# <- { "return": {} }
+#
 ##
 { 'command': 'blockdev-add', 'data': 'BlockdevOptions', 'boxed': true }