Merge changes from topic "st_docs_update" into integration

* changes:
  docs(st): set OP-TEE as default BL32
  docs(st): one device flag for ST platforms
diff --git a/docs/plat/st/stm32mp1.rst b/docs/plat/st/stm32mp1.rst
index b6e4b0d..39a43ee 100644
--- a/docs/plat/st/stm32mp1.rst
+++ b/docs/plat/st/stm32mp1.rst
@@ -115,8 +115,9 @@
     make stm32mp15_trusted_defconfig
     make DEVICE_TREE=stm32mp157c-ev1 all
 
-OP-TEE (optional)
-_________________
+OP-TEE (recommended)
+____________________
+OP-TEE is the default BL32 supported for STMicroelectronics platforms.
 
 .. code:: bash
 
@@ -125,9 +126,10 @@
         CFG_EMBED_DTB_SOURCE_FILE=stm32mp157c-ev1.dts
 
 
-TF-A BL32 (SP_min)
-__________________
+TF-A BL32 (SP_min) (not recommended)
+____________________________________
 If you choose not to use OP-TEE, you can use TF-A SP_min.
+This is not the recommended BL32 to use, and will have very limited support.
 To build TF-A BL32, and its device tree file:
 
 .. code:: bash
@@ -217,4 +219,4 @@
 .. _STM32MP1 Series: https://www.st.com/en/microcontrollers-microprocessors/stm32mp1-series.html
 .. _STM32MP1 part number codification: https://wiki.st.com/stm32mpu/wiki/STM32MP15_microprocessor#Part_number_codification
 
-*Copyright (c) 2023, STMicroelectronics - All Rights Reserved*
+*Copyright (c) 2023-2024, STMicroelectronics - All Rights Reserved*
diff --git a/docs/plat/st/stm32mpus.rst b/docs/plat/st/stm32mpus.rst
index 931dd57..ab6d8fe 100644
--- a/docs/plat/st/stm32mpus.rst
+++ b/docs/plat/st/stm32mpus.rst
@@ -45,6 +45,8 @@
 - ``STM32MP_UART_PROGRAMMER``
 - ``STM32MP_USB_PROGRAMMER``
 
+Only one storage or serial device should be selected in the build command line,
+to save space and not overflow SYSRAM size, or else the platform won't build or boot.
 
 Other configuration flags:
 
@@ -75,4 +77,4 @@
 
 --------------
 
-*Copyright (c) 2023, STMicroelectronics - All Rights Reserved*
+*Copyright (c) 2023-2024, STMicroelectronics - All Rights Reserved*