add README

README.md

+Turku PET Centre - Convert SVG file(s) to PNG format
+====================================================
+
+The script can be used to convert SVG file(s) to PNG format.
+Script is dependent on [Inkscape](https://inkscape.org), which is a free, open source,
+vector graphics software.
+After Inkscape is installed, the correct path for executable file must be
+defined in the start of the batch file. 
+
+Note that while Inkscape can be found in Microsoft Store, that version cannot be used with
+this script.