qapi: Fix malformed "Since:" section tags

"Since X.Y" is not recognized as a tagged section, and therefore not
formatted as such in generated documentation.  Fix by adding the
required colon.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20220422132807.1704411-1-armbru@redhat.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>

qapi/crypto.json

@@ -357,8 +357,7 @@
 #                 password to use to retrieve current master key.
 #                 Defaults to the same secret that was used to open the image
 #
-#
-# Since 5.1
+# Since: 5.1
 ##
 { 'struct': 'QCryptoBlockAmendOptionsLUKS',
   'data': { 'state': 'QCryptoBlockLUKSKeyslotState',

qapi/machine.json

@@ -972,7 +972,7 @@
 # preconfigure stage to configure numa mapping before initializing
 # machine.
 #
-# Since 3.0
+# Since: 3.0
 ##
 { 'command': 'set-numa-node', 'boxed': true,
   'data': 'NumaOptions',

qapi/misc.json

@@ -188,7 +188,7 @@
 # Features:
 # @unstable: This command is experimental.
 #
-# Since 3.0
+# Since: 3.0
 #
 # Returns: nothing
 #

qga/qapi-schema.json

@@ -950,7 +950,7 @@
 #         by device mapper
 # @smart: disk smart information (Since 7.1)
 #
-# Since 5.2
+# Since: 5.2
 ##
 { 'struct': 'GuestDiskInfo',
   'data': {'name': 'str', 'partition': 'bool', '*dependencies': ['str'],