Adding script capability

doc/scripts.mdwn

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+# Scripts
+
+The Plinth front end should not directly change any aspect of the
+underlying operating system.  Instead, it should call upon scripts,
+either by shell command or (for python modules) via import.
+
+Scripts live in `/scripts`.  They should have the following
+characteristics:
+
+* Do only one thing
+
+* Require no interaction beyond passing parameters or commandline
+  arguments
+
+* Change the operation of the services and applications of the Freedom
+  Plug and nothing else.
+
+* If a script is a python file, it should be *both* usable from the
+  commandline and importable as a python module.
+
+The scripts should be of general utility.  They should be usable to
+admin and configure the system even in the absence of Plinth.  These
+scripts are the only supported method of making changes to a Freedom
+Plug, whtether by SSH or via Plinth.