README: document the new tidy-html5 test suite requirement

diff --git a/README b/README
index 2dcf40309a83f95fec49f976ea2482f4d30c5478..7f9775a9b106cac63cce99ef32fd3281da061615 100644 (file)
--- a/README
+++ b/README
@@ -5,6 +5,8 @@ Build requirements:
   3. The "fontforge" program.
   4. The "xsltproc" program from libxslt.
 
+To run the test suite, you'll also need the "tidy-html5" program.
+
 SVG Tricks:
 
 1. To remove a "transform" from a group (like the bus) that was