Fix spelling error

src/ffoo/saturnin_www.sh

     #
     # Scan stdin for what looks like URI, ID or keyword
     #
-    # Output URIS: first what were apparent uris, then IDs converted to
+    # Output URIs: first what were apparent uris, then IDs converted to
     # URIs, then equal sign expressions, then things that looked like
     # kw expressions, converted to URIs.
     #