Merge pull request #7603 from kenjis/fix-docs-message.rst

docs: fix message.rst

Author: kenjis

user_guide_src/source/incoming/message.rst

@@ -151,15 +151,16 @@ Class Reference
         :returns: The current HTTP protocol version
         :rtype: string
 
-        Returns the message's current HTTP protocol. If none has been set, will return ``null``.
-        Acceptable values are ``1.0``, ``1.1`` and ``2.0``.
+        Returns the message's current HTTP protocol. If none has been set, will
+        return ``1.1``.
 
     .. php:method:: setProtocolVersion($version)
 
         :param string $version: The HTTP protocol version
         :returns: The current message instance
         :rtype: CodeIgniter\\HTTP\\Message
 
-        Sets the HTTP protocol version this Message uses. Valid values are ``1.0``, ``1.1`` and ``2.0``:
+        Sets the HTTP protocol version this Message uses. Valid values are
+        ``1.0``, ``1.1``, ``2.0`` and ``3.0``:
 
         .. literalinclude:: message/010.php