Add Readme to the Lua script folder

scripts/README

@@ -0,0 +1,29 @@
+Ardour Lua Scripts
+==================
+
+https://manual.ardour.org/lua-scripting/
+
+For upstream script addition, please file a pull-request at
+https://github.com/Ardour/ardour/tree/master/scripts
+
+Script Naming conventions:
+
+^_
+ A script filename with a leading underscore indicates an example script.
+ These scripts are only available from ardour's git repository and not
+ installed nor included with binary bundles.
+
+^__
+ Scripts with a filename starting with two underscores are excluded from
+ unit-tests.  This is currently the case for convolver, fluidsynth and
+ plugin-modulation.
+ They depend on external files (soundfont, impulse-response) or a specific
+ session-setup (plugin-modulation needs an automatable plugin).
+
+^s_
+ A filename beginning with "s_" indicates a code snippet.
+ These scripts can only be used in the interactive interpreter
+ (Window > Scripting). They may be useful by themselves or handy for copy/edit
+ to create EditorActions.
+ The filename prefix is only for convenience, "type" = "Snippet" is used when
+ scripts are listed at runtime.