added documentation

README.md

@@ -1,3 +1,13 @@
 # darktable_to_lightgallery
 
-A combination of a darktable lua script and python scripts to export files in darktable and automatically create a js lightgallery from them
+A combination of a darktable lua script and python scripts to export files in darktable and automatically create a js lightgallery from them
+
+# The darktable part
+
+consists of export_to_lightgallery.lua. This script adds a module to the right side of darktable, showing
+  * a entry field for the gallery title
+  * a directory chooser for the target directory
+  * a entry field for the uplink url
+  * a checkbox for the attachment of the "photography|published|gallery|family" tag
+  * a "Run"-Button
+  * a "Help" Link