[DOCS] Create install-upgrade folder (#196)

Author: lcawl

docs/index.asciidoc renamed to docs/en/install-upgrade/index.asciidoc

@@ -1,8 +1,11 @@
 [[elastic-stack]]
-= Elastic Stack
+= Installation and Upgrade Guide
+
+:es-repo-dir:        {docdir}/../../../../elasticsearch/docs
+:kib-repo-dir:       {docdir}/../../../../kibana/docs
 
 include::{asciidoc-dir}/../../shared/attributes.asciidoc[]
-include::{docdir}/../../elasticsearch/docs/Versions.asciidoc[]
+include::{es-repo-dir}/Versions.asciidoc[]
 
 == Overview
 
@@ -30,5 +33,3 @@ include::installing-stack.asciidoc[]
 
 include::upgrading-stack.asciidoc[]
 
-
-