cmake: Add check and warning for module docs

src/modules/CMakeLists.txt

@@ -107,8 +107,14 @@ function(add_module_group group_name group_modules)
         )
         # Add the module to the list of added modules
         set_property(GLOBAL APPEND PROPERTY ADDED_MODULES_LIST ${module_name})
-        docs_add_module(${group_name} ${module_name})
-        set_property(GLOBAL APPEND PROPERTY ALL_MODULE_DOC_TARGETS ${module_name}_doc)
+        if(NOT EXISTS ${CMAKE_SOURCE_DIR}/src/modules/${module_name}/doc/${module_name}.xml)
+          message(WARNING "No documentation found for module ${module_name}.")
+          return()
+        else()
+          docs_add_module(${group_name} ${module_name})
+          set_property(GLOBAL APPEND PROPERTY ALL_MODULE_DOC_TARGETS ${module_name}_doc)
+        endif()
+
       else()
         message(FATAL_ERROR "Module directory ${module_path} does not exist.")
       endif()