docs: serial: convert docs to ReST and rename to *.rst

The converted files are focused at the Kernel internal API,
so, this is a good candidate for the kernel API set of books.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/Kconfig

@@ -175,7 +175,7 @@ config ROCKETPORT
 	  This driver supports Comtrol RocketPort and RocketModem PCI boards.   
           These boards provide 2, 4, 8, 16, or 32 high-speed serial ports or
           modems.  For information about the RocketPort/RocketModem  boards
-          and this driver read <file:Documentation/serial/rocket.txt>.
+          and this driver read <file:Documentation/serial/rocket.rst>.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called rocket.
@@ -193,7 +193,7 @@ config CYCLADES
 	  your Linux box, for instance in order to become a dial-in server.
 
 	  For information about the Cyclades-Z card, read
-	  <file:Documentation/serial/README.cycladesZ>.
+	  <file:Documentation/serial/cyclades_z.rst>.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called cyclades.

drivers/tty/serial/ucc_uart.c

@@ -1081,7 +1081,7 @@ static int qe_uart_verify_port(struct uart_port *port,
 }
 /* UART operations
  *
- * Details on these functions can be found in Documentation/serial/driver
+ * Details on these functions can be found in Documentation/serial/driver.rst
  */
 static const struct uart_ops qe_uart_pops = {
 	.tx_empty       = qe_uart_tx_empty,