doc: add commas in macro arguments to Kconfig tips

Kconfig uses commas to separate macro arguments.

Improve Kconfig documentation by describing to users how this can be
handled when using devicetree Kconfig macros when using devicetree names
which may have commas in them.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

doc/build/kconfig/tips.rst

@@ -593,6 +593,30 @@ invisible:
    [*] All my children are invisible  ----
 
 
+Commas in macro arguments
+*************************
+
+Kconfig uses commas to separate macro arguments.
+This means a construct like this will fail:
+
+.. code-block:: none
+
+    config FOO
+        bool
+        default y if $(dt_chosen_enabled,"zephyr,bar")
+
+To solve this problem, create a variable with the text and use this variable as
+argument, as follows:
+
+.. code-block:: none
+
+    DT_CHOSEN_ZEPHYR_BAR := zephyr,bar
+
+    config FOO
+        bool
+        default y if $(dt_chosen_enabled,$(DT_CHOSEN_ZEPHYR_BAR))
+
+
 Checking changes in menuconfig/guiconfig
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