[contextualprocess] Document new behavior for compound keys

src/modules/contextualprocess/contextualprocess.conf

@@ -13,6 +13,17 @@
 # to the variable's value. If the variable has that particular value, the
 # corresponding value (script) is executed.
 #
+# The variable **may** contain dots, in which case the dot is used
+# to select into maps inside global storage, e.g.
+#
+#   - *firmwareType* is a simple global name
+#   - *branding.bootloader* is the *bootloader* value in the *branding* map
+#
+# Only a few global storage entries have well-defined sub-maps;
+# branding is one of them, and *filesystem_use* is another. Note that
+# variable names with dots **must** be quoted, or you will get a YAML error.
+#
+#
 # You can check for an empty value with "".
 #
 # As a special case, the value-check "*" matches any value, but **only**
@@ -44,3 +55,6 @@ firmwareType:
     bios:   "-pkg remove bios-firmware"
     "":     "/bin/false no-firmware-type-set"
     "*":    "/bin/false some-other-firmware-value"
+"branding.shortVersion":
+    "2020.2": "/bin/false february"
+    "2019.4": "/bin/true april"