doc: Render Marvell platform documents

The documentation for Marvell platforms was not included in the
rendered document output until now because, while it was mostly
valid RST format, the files were saved with a .txt extension.

This patch corrects some RST formatting errors, creates a document
tree (index page) for the Marvell documents, and adds the Marvell
subtree to the main index.

Change-Id: Id7d4ac37eded636f8f62322a153e1e5f652ff51a
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/plat/marvell/misc/mvebu-iob.rst b/docs/plat/marvell/misc/mvebu-iob.rst
new file mode 100644
index 0000000..d02a7e8
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+Marvell IOB address decoding bindings
+=====================================
+
+IO bridge configration driver (3rd stage address translation) for Marvell Armada 8K and 8K+ SoCs.
+
+The IOB includes a description of the address decoding configuration.
+
+IOB supports up to n (in CP110 n=24) windows for external memory transaction.
+When a transaction passes through the IOB, its address is compared to each of
+the enabled windows. If there is a hit and it passes the security checks, it is
+advanced to the target port.
+
+Mandatory functions
+-------------------
+
+- marvell_get_iob_memory_map
+     Returns the IOB windows configuration and the number of windows
+
+Mandatory structures
+--------------------
+
+- iob_memory_map
+     Array that includes the configuration of the windows. Every window/entry is
+     a struct which has 3 parameters:
+
+       - Base address of the window
+       - Size of the window
+       - Target-ID of the window
+
+Target ID options
+-----------------
+
+- **0x0** = Internal configuration space
+- **0x1** = MCI0
+- **0x2** = PEX1_X1
+- **0x3** = PEX2_X1
+- **0x4** = PEX0_X4
+- **0x5** = NAND flash
+- **0x6** = RUNIT (NOR/SPI/BootRoom)
+- **0x7** = MCI1
+
+Example
+-------
+
+.. code:: c
+
+	struct addr_map_win iob_memory_map[] = {
+		{0x00000000f7000000,	0x0000000001000000,	PEX1_TID}, /* PEX1_X1 window */
+		{0x00000000f8000000,	0x0000000001000000,	PEX2_TID}, /* PEX2_X1 window */
+		{0x00000000f6000000,	0x0000000001000000,	PEX0_TID}, /* PEX0_X4 window */
+		{0x00000000f9000000,	0x0000000001000000,	NAND_TID}  /* NAND window */
+	};