docs(maintainers): update missing files related to EL3 SPMC

Few header files are added to the list maintained by EL3 SPMC
code owner.

Also added missing copyright license footer message.

Change-Id: I72afe4c4e1280ef64610a5efe6d1b0e2c9727bb0
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
diff --git a/docs/about/maintainers.rst b/docs/about/maintainers.rst
index 1f68927..1dda0ff 100644
--- a/docs/about/maintainers.rst
+++ b/docs/about/maintainers.rst
@@ -114,6 +114,8 @@
 :|M|: Marc Bonnici <marc.bonnici@arm.com>
 :|G|: `marcbonnici`_
 :|F|: services/std_svc/spm/el3_spmc/\*
+:|F|: include/services/el3_spmc\_\*
+:|F|: include/services/spmc_svc.h
 
 Secure Partition Manager Dispatcher (SPMD)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -1061,3 +1063,7 @@
 .. _vwadekar: https://github.com/vwadekar
 .. _xueliang-zhong-arm: https://github.com/xueliang-zhong-arm
 .. _Yann-lms: https://github.com/Yann-lms
+
+--------------
+
+*Copyright (c) 2019-2024, Arm Limited and Contributors. All rights reserved.*