Add Creation With Upload extension

protocol.md

@@ -351,6 +351,20 @@ If the length of the upload exceeds the maximum, which MAY be specified using
 the `Tus-Max-Size` header, the Server MUST respond with the
 `413 Request Entity Too Large` status.
 
+The Client MAY include the entire or a chunk of the data, which is meant to be
+uploaded, in the body of the `POST` request. In this case, similar rules as for
+the `PATCH` request and response apply. The Client MUST include the
+`Content-Type: application/offset+octet-stream` header. The Server SHOULD accept
+as many bytes as possible and MUST include the `Upload-Offset` in the response
+and MUST set its value to the offset of the upload after applying the accepted
+bytes. If the Server supports the functionality described in this paragraph, it
+MUST advertise this by including the `creation-with-chunk` value to the
+`Tus-Extension` header. The Client SHOULD verify that the Server is capable of
+handling this cases before sending the `POST` request. In addition, the Client
+SHOULD include the `Expect: 100-continue` header in the request to receive
+early feedback from the Server whether it will accept the creation request
+before attempting to transfer the first chunk.
+
 The Server MUST acknowledge a successful upload creation with the `201 Created`
 status. The Server MUST set the `Location` header to the URL of the created
 resource. This URL MAY be absolute or relative.