README: Add link to demo web interface

README.rst

@@ -14,6 +14,8 @@ patterns, dashes and transformations.
 Raster images can either be vectorized through contour tracing (like gerbolyze v1.0 did) or they can be embedded using
 high-resolution grayscale emulation while (mostly) guaranteeing trace/space design rules.
 
+Try gerbolyze online at https://tsugi.kokoroyukuma.de/gerboweb
+
 .. figure:: pics/pcbway_sample_02_small.jpg
   :width: 800px
 
@@ -184,6 +186,16 @@ This is the algorithm svg-flatten uses to process an SVG.
 * for KiCAD S-Expression export: vector-composite results using CavalierContours: subtract each clear output primitive
   from all previous dark output primitives
 
+Web interface
+-------------
+
+You can try gerbolyze online at https://tsugi.kokoroyukuma.de/gerboweb
+
+The web interface does not expose all of gerbolyze's bells and whistles, but it allows you to simply paste a single SVG
+file on a board to try out gerbolyze. Upload your design on the web interface, then download the template for either the
+top or bottom side, and put your artwork on the appropriate layer of that template using Inkscape_. Finally, upload the
+modified template and let gerbolyze process your design.
+
 Command-line usage
 ------------------
 .. _command_line_usage: