Open source BazelDocumentationTest (and fix documentation).

--
MOS_MIGRATED_REVID=108145081
diff --git a/site/BUILD b/site/BUILD
new file mode 100644
index 0000000..58365fe
--- /dev/null
+++ b/site/BUILD
@@ -0,0 +1,3 @@
+exports_files(
+    ["docs/bazel-user-manual.html"],
+)