MLECO-3186: Each use case should same namespace convention as KWS and ASR

Certain UCs required additional work due to case context variables which also
became part of a namespace in generated files.
Solution was to declare these extra variables as part of the UC namespace in the respective model.hpp files.
Additional changes to standardise use of namespaces may be required - proposing new task.

Minor typo and rewording of customizing.md in relevant sections included.

Signed-off-by: Liam Barry <liam.barry@arm.com>
Change-Id: Ie78f82a30be252cb841136ea5115f21fc8d762cb
diff --git a/source/use_case/object_detection/src/UseCaseHandler.cc b/source/use_case/object_detection/src/UseCaseHandler.cc
index 4d0877a..e9bcd4a 100644
--- a/source/use_case/object_detection/src/UseCaseHandler.cc
+++ b/source/use_case/object_detection/src/UseCaseHandler.cc
@@ -27,6 +27,9 @@
 
 namespace arm {
 namespace app {
+    namespace object_detection {
+        extern const int channelsImageDisplayed;
+    } /* namespace object_detection */
 
     /**
      * @brief           Presents inference results along using the data presentation
@@ -122,9 +125,13 @@
 
             /* Display image on the LCD. */
             hal_lcd_display_image(
-                (channelsImageDisplayed == 3) ? currImage : dstPtr,
-                inputImgCols, inputImgRows, channelsImageDisplayed,
-                dataPsnImgStartX, dataPsnImgStartY, dataPsnImgDownscaleFactor);
+                (arm::app::object_detection::channelsImageDisplayed == 3) ? currImage : dstPtr,
+                inputImgCols,
+                inputImgRows,
+                arm::app::object_detection::channelsImageDisplayed,
+                dataPsnImgStartX,
+                dataPsnImgStartY,
+                dataPsnImgDownscaleFactor);
 
             /* Display message on the LCD - inference running. */
             hal_lcd_display_text(str_inf.c_str(), str_inf.size(),