doc: Reformat platform port documents

The platform port documents are not very standardised right now and
they don't integrate properly into the document tree so:

1) Make sure each port has a proper name and title (incl. owner)
2) Correct use of headings, subheadings, etc in each port
3) Resolve any naming conflicts between documents

Change-Id: I4c2da6f57172b7f2af3512e766ae9ce3b840b50f
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/plat/imx8m.rst b/docs/plat/imx8m.rst
index a69f022..8acd13c 100644
--- a/docs/plat/imx8m.rst
+++ b/docs/plat/imx8m.rst
@@ -1,5 +1,5 @@
-Description
-===========
+NXP i.MX 8M Series
+==================
 
 The i.MX 8M family of applications processors based on Arm Corte-A53 and Cortex-M4
 cores provide high-performance computing, power efficiency, enhanced system
@@ -7,15 +7,15 @@
 edge node computing, streaming multimedia, and machine learning applications.
 
 Boot Sequence
-=============
+-------------
 
 Bootrom --> SPL --> BL31 --> BL33(u-boot) --> Linux kernel
 
 How to build
-============
+------------
 
 Build Procedure
----------------
+~~~~~~~~~~~~~~~
 
 -  Prepare AARCH64 toolchain.
 
@@ -34,7 +34,7 @@
    Target_SoC should be "imx8mm" for i.MX8MM SoC.
 
 Deploy TF-A Images
------------------
+~~~~~~~~~~~~~~~~~~
 
 TF-A binary(bl31.bin), u-boot-spl.bin u-boot-nodtb.bin and dtb are combined
 together to generate a binary file called flash.bin, the imx-mkimage tool is