docs(maintainers): add maintainers for i.MX9 SoCs

Add maintainers for NXP i.MX9 SoC family.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Change-Id: I6dd694af56da9f4d241fda28b781254586b5f462
diff --git a/docs/about/maintainers.rst b/docs/about/maintainers.rst
index 663859f..a27c26c 100644
--- a/docs/about/maintainers.rst
+++ b/docs/about/maintainers.rst
@@ -619,6 +619,13 @@
 :|F|: docs/plat/imx8m.rst
 :|F|: plat/imx/imx8m/
 
+NXP i.MX9 platform port
+^^^^^^^^^^^^^^^^^^^^^^^^
+:|M|: Jacky Bai <ping.bai@nxp.com>
+:|G|: `JackyBai`_
+:|F|: docs/plat/imx9.rst
+:|F|: plat/imx/imx93/
+
 NXP QorIQ Layerscape common code for platform ports
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 :|M|: Pankaj Gupta <pankaj.gupta@nxp.com>