Merge pull request #21 from szabosteve/add.es.repo

[DOCS] Adds low-level subsection from ES repo to TOC

Author: szabosteve

docs/index.asciidoc

@@ -5,4 +5,5 @@ include::{asciidoc-dir}/../../shared/attributes.asciidoc[]
 
 include::introduction.asciidoc[]
 include::installation.asciidoc[]
-include::connecting.asciidoc[]
+include::connecting.asciidoc[]
+include::{elasticsearch-root}/docs/java-rest/low-level/index.asciidoc[]