the new name for index (args.output) will be used for index refernces as well

html/ldoc.ltp

@@ -28,7 +28,7 @@
 <h1>$(ldoc.project)</h1>
 # if not ldoc.single then
 <ul>
-  <li><a href="../index.html">Index</a></li>
+  <li><a href="../$(ldoc.output).html">Index</a></li>
 </ul>
 # else
 <p>$(ldoc.description)</p>

ldoc.lua

@@ -648,6 +648,7 @@ function generate_output()
    -- write out the per-module documentation
    if not ldoc.single then
       ldoc.css = '../'..css
+      ldoc.output = args.output
       for kind, modules in project() do
          kind = kind:lower()
          check_directory(args.dir..kind)