Add ldoc template for lua module documentation

The template can be used instead of the default template by calling ldoc
with the `-l doc` option, where *doc* is the directory of the template.

doc/ldoc.ltp

@@ -0,0 +1,38 @@
+# local iter = ldoc.modules.iter
+# local M = ldoc.markup
+
+<h1>Module $(module.name)</h1>
+
+<p>$(M(module.summary))</p>
+
+# for kind, items in module.kinds() do
+
+<h2>$(kind)</h2>
+  <dl>
+#  for item in items() do ldoc.item = item -- provides context for M()
+    <dt><span id="$(item.name)"><code>$(ldoc.display_name(item))</code></span></dt>
+    <dd>
+      <p>$(item.summary)</p>
+#  if item.params and #item.params > 0 then
+      $(module.kinds:type_of(item).subnames):
+      <dl>
+#     for p in iter(item.params) do
+        <dt><code>$(p)</code>:</dt>
+        <dd>$(M(item.params.map[p]))</dd>
+#     end -- for
+      </dl>
+#   end -- if params
+#   if item.ret then
+    <p>Returns: $(item.ret[1])</p>
+#   end -- if returns
+#   if item.usage then
+    <p>Usage:</p>
+    <pre><code>$(item.usage[1])</code></pre>
+#   end -- if usage
+#   if item.see then
+    See also: <a href="#$(item.see[1].label)">$(item.see[1].label)</a>
+
+#   end -- if see
+# end -- for items
+  </dl>
+# end -- for kinds