doc: connectivity: networking: Update CMake linker info to CoAP server

Add missing entry to the documentation to also support CMake linker
generator with CoAP services.
Update hard coded value with linker script defined value.

Signed-off-by: Pieter De Gendt <[email protected]>

Author: pdgendt

doc/connectivity/networking/api/coap_server.rst

@@ -34,15 +34,21 @@ prefixed with ``coap_resource_`` and added to a linker file:
 
     #include <zephyr/linker/iterable_sections.h>
 
-    ITERABLE_SECTION_RAM(coap_resource_my_service, 4)
+    ITERABLE_SECTION_RAM(coap_resource_my_service, Z_LINK_ITERABLE_SUBALIGN)
 
 Add this linker file to your application using CMake:
 
 .. code-block:: cmake
     :caption: ``CMakeLists.txt``
 
+    # Support LD linker template
     zephyr_linker_sources(DATA_SECTIONS sections-ram.ld)
 
+    # Support CMake linker generator
+    zephyr_iterable_section(NAME coap_resource_my_service
+                            GROUP DATA_REGION ${XIP_ALIGN_WITH_INPUT}
+                            SUBALIGN ${CONFIG_LINKER_ITERABLE_SUBALIGN})
+
 You can now define your service as part of the application:
 
 .. code-block:: c