Switch to side-by-side view

--- a/website/idxthreads/Makefile
+++ b/website/idxthreads/Makefile
@@ -1,2 +1,7 @@
-threadingRecoll.html : threadingRecoll.txt nothreads.png
-	asciidoc threadingRecoll.txt
+.SUFFIXES: .txt .html
+
+.txt.html:
+	asciidoc $<
+
+all: threadingRecoll.html forkingRecoll.html xapDocCopyCrash.html
+