[DOCS] Build ES Reference from x-pack-elasticsearch (elastic/x-pack-elasticsearch#1722)

* [DOCS] Build ES Reference from x-pack-elasticsearch

* [DOCS] Added es-test-dir attribute

* [DOCS] Added plugins-examples-dir attribute

Original commit: elastic/x-pack-elasticsearch@05714eb8ca

docs/en/Versions.asciidoc

@@ -0,0 +1,62 @@
+:version:               6.0.0-alpha2
+:major-version:         6.x
+:lucene_version:        7.0.0-SNAPSHOT
+:lucene_version_path:   7_0_0
+:branch:                master
+:jdk:                   1.8.0_131
+
+//////////
+release-state can be: released | prerelease | unreleased
+//////////
+
+:release-state:   prerelease
+
+:ref:             https://www.elastic.co/guide/en/elasticsearch/reference/{branch}
+:defguide:        https://www.elastic.co/guide/en/elasticsearch/guide/master
+:painless:        https://www.elastic.co/guide/en/elasticsearch/painless/master
+:plugins:         https://www.elastic.co/guide/en/elasticsearch/plugins/{branch}
+:javaclient:      https://www.elastic.co/guide/en/elasticsearch/client/java-api/{branch}
+:xpack-ref:       https://www.elastic.co/guide/en/x-pack/{branch}
+:logstash:        https://www.elastic.co/guide/en/logstash/{branch}
+:kibana:          https://www.elastic.co/guide/en/kibana/{branch}
+:issue:           https://github.com/elastic/elasticsearch/issues/
+:pull:            https://github.com/elastic/elasticsearch/pull/
+
+:docker-image:    docker.elastic.co/elasticsearch/elasticsearch:{version}
+:plugin_url:      https://artifacts.elastic.co/downloads/elasticsearch-plugins
+
+:xpack:           X-Pack
+:security:        X-Pack security
+:monitoring:      X-Pack monitoring
+:watcher:         Watcher
+:reporting:       X-Pack reporting
+:graph:           X-Pack graph
+:searchprofiler:  X-Pack search profiler
+:xpackml:         X-Pack machine learning
+:ml:              machine learning
+:es:              Elasticsearch
+:kib:             Kibana
+:dfeed:           datafeed
+:dfeeds:          datafeeds
+:dfeed-cap:       Datafeed
+:dfeeds-cap:      Datafeeds
+
+:xes-repo-dir:    {docdir}
+
+///////
+Javadoc roots used to generate links from Painless's API reference
+///////
+:java8-javadoc: https://docs.oracle.com/javase/8/docs/api
+:java9-javadoc: http://download.java.net/java/jigsaw/docs/api
+:joda-time-javadoc: http://www.joda.org/joda-time/apidocs
+:lucene-core-javadoc: http://lucene.apache.org/core/{lucene_version_path}/core
+
+ifeval::["{release-state}"=="unreleased"]
+:elasticsearch-javadoc: https://snapshots.elastic.co/javadoc/org/elasticsearch/elasticsearch/{version}-SNAPSHOT
+:painless-javadoc: https://snapshots.elastic.co/javadoc/org/elasticsearch/painless/lang-painless/{version}-SNAPSHOT
+endif::[]
+
+ifeval::["{release-state}"!="unreleased"]
+:elasticsearch-javadoc: https://artifacts.elastic.co/javadoc/org/elasticsearch/elasticsearch/{version}
+:painless-javadoc: https://artifacts.elastic.co/javadoc/org/elasticsearch/painless/lang-painless/{version}
+endif::[]

docs/en/index-all.asciidoc

@@ -0,0 +1,11 @@
+[[elasticsearch-reference]]
+= Elasticsearch Reference
+
+:include-xpack:         true
+
+:es-repo-dir:           {docdir}/../../../../elasticsearch/docs
+:es-test-dir:           {docdir}/../../../../elasticsearch/docs/src/test
+:plugins-examples-dir:  {docdir}/../../../../elasticsearch/plugins/examples
+
+include::Versions.asciidoc[]
+include::index-shared.asciidoc[]

docs/en/index-shared.asciidoc

@@ -0,0 +1,47 @@
+
+
+include::{es-repo-dir}/reference/getting-started.asciidoc[]
+
+include::{es-repo-dir}/reference/setup.asciidoc[]
+
+include::{es-repo-dir}/reference/migration/index.asciidoc[]
+
+include::{es-repo-dir}/reference/api-conventions.asciidoc[]
+
+include::{es-repo-dir}/reference/docs.asciidoc[]
+
+include::{es-repo-dir}/reference/search.asciidoc[]
+
+include::{es-repo-dir}/reference/aggregations.asciidoc[]
+
+include::{es-repo-dir}/reference/indices.asciidoc[]
+
+include::{es-repo-dir}/reference/cat.asciidoc[]
+
+include::{es-repo-dir}/reference/cluster.asciidoc[]
+
+ifdef::include-xpack[]
+include::rest-api/index.asciidoc[]
+endif::include-xpack[]
+
+include::{es-repo-dir}/reference/query-dsl.asciidoc[]
+
+include::{es-repo-dir}/reference/mapping.asciidoc[]
+
+include::{es-repo-dir}/reference/analysis.asciidoc[]
+
+include::{es-repo-dir}/reference/modules.asciidoc[]
+
+include::{es-repo-dir}/reference/index-modules.asciidoc[]
+
+include::{es-repo-dir}/reference/ingest.asciidoc[]
+
+include::{es-repo-dir}/reference/how-to.asciidoc[]
+
+include::{es-repo-dir}/reference/testing.asciidoc[]
+
+include::{es-repo-dir}/reference/glossary.asciidoc[]
+
+include::{es-repo-dir}/reference/release-notes.asciidoc[]
+
+include::{es-repo-dir}/reference/redirects.asciidoc[]

docs/en/index.asciidoc

@@ -0,0 +1,9 @@
+[[elasticsearch-reference]]
+= Elasticsearch Reference
+
+:es-repo-dir:           {docdir}/../../../../elasticsearch/docs
+:es-test-dir:           {docdir}/../../../../elasticsearch/docs/src/test
+:plugins-examples-dir:  {docdir}/../../../../elasticsearch/plugins/examples
+
+include::Versions.asciidoc[]
+include::index-shared.asciidoc[]