Use new module hierarchy for Ngnd Driver.

Added comments to Timer Module CMakeLists.

zephyr/modules/owntech_ngnd_driver/zephyr/CMakeLists.txt

-
 if(CONFIG_OWNTECH_NGND_DRIVER)
-  zephyr_include_directories(.)
-
+  # Select directory to add to the include path
+  zephyr_include_directories(./public_include)
+  # Define the current folder as a Zephyr library
   zephyr_library()
+  # Select source files to be compiled
   zephyr_library_sources(
-    owntech_ngnd_driver.c
+    src/owntech_ngnd_driver.c
     )
 endif()

zephyr/modules/owntech_ngnd_driver/zephyr/Kconfig

-
 config OWNTECH_NGND_DRIVER
 	bool "Enable OwnTech ngnd driver"
 	default y

zephyr/modules/owntech_timer_driver/zephyr/CMakeLists.txt

 if(CONFIG_OWNTECH_TIMER_DRIVER)
+  # Select directory to add to the include path
   zephyr_include_directories(./public_include)
+  # Define the current folder as a Zephyr library
   zephyr_library()
+  # Select source files to be compiled
   zephyr_library_sources(
     ./src/stm32_timer_driver.c
     )