[DOCS] Adds kib-repo-dir attribute

Author: lcawl

x-pack/docs/en/index.asciidoc

@@ -12,6 +12,7 @@
 :wikipedia:         https://en.wikipedia.org/wiki
 
 :xkb-repo-dir:      {docdir}/../../../../kibana/x-pack/docs/en
+:kib-repo-dir:      {docdir}/../../../../kibana/docs
 :xes-repo-dir:      {docdir}/../../../../elasticsearch/x-pack/docs/en
 
 include::{asciidoc-dir}/../../shared/versions.asciidoc[]