[interactiveterminal] Document config

src/modules/interactiveterminal/interactiveterminal.conf

@@ -1,2 +1,14 @@
+# The interactive terminal provides a konsole (terminal) window
+# during the installation process. The terminal runs in the
+# host system, so you will need to change directories to the
+# target system to examine the state there.
+#
+# The one configuration key *command*, if defined, is passed
+# as a command to run in the terminal window before any user
+# input is accepted. The user must exit the terminal manually
+# or click *next* to proceed to the next installation step.
+#
+# If no command is defined, no command is run and the user
+# gets a plain terminal session.
 ---
 command:        "echo Hello"