Thanks for the report!  We recently moved all of these rules to their own repos (e.g., https://github.com/bazelbuild/rule_appengine), and I think we're still updating how their documentation is generated.

Missing docs pages / broken links
I was reading through the Docs on http://bazel.io/docs/install.html and there are some broken links on the Skylark Rules section of the side menu.

These links return 404:
- Java AppEngine - http://bazel.io/docs/be/appengine.html
- C# - http://bazel.io/docs/be/dotnet.html
- D - http://bazel.io/docs/be/d.html
- Groovy - http://bazel.io/docs/be/groovy.html
- Go - http://bazel.io/docs/be/go.html
- Sass - http://bazel.io/docs/be/sass.html

This link returns a page with a redirect link, and that link returns 404:
- Scala - http://bazel.io/docs/be/scala.html

Apologies if this is the wrong repo to report this, but I couldn't find a better one in the bazelbuild org.

src/main/java/com/google/devtools/build/docgen/templates/be/be-nav.vm
src/main/java/com/google/devtools/build/docgen/templates/be/be-nav.vm
diff --git a/src/main/java/com/google/devtools/build/docgen/templates/be/be-nav.vm b/src/main/java/com/google/devtools/build/docgen/templates/be/be-nav.vm
index 0aa490835df6be..671b5a691deefe 100644
--- a/src/main/java/com/google/devtools/build/docgen/templates/be/be-nav.vm
+++ b/src/main/java/com/google/devtools/build/docgen/templates/be/be-nav.vm
@@ -34,7 +34,7 @@
   <li><a href="${bazelbuildGithub}/rules_go" target="_blank">Go</a></li>
   <li><a href="${bazelbuildGithub}/rules_jsonnet" target="_blank">Jsonnet</a></li>
   <li><a href="${path}/pkg.html">Packaging</a></li>
-  <li><a href="${bazelbuildGithub}/rules_rust target="_blank"">Rust</a></li>
+  <li><a href="${bazelbuildGithub}/rules_rust" target="_blank"">Rust</a></li>
   <li><a href="${bazelbuildGithub}/rules_sass" target="_blank">Sass</a></li>
   <li><a href="${bazelbuildGithub}/rules_scala" target="_blank">Scala</a></li>
 </ul>
