Explain
-search engine status,
-concepts
-and semantic configuration

PRs :

• Semantic Config https://github.com/ezsystems/ezpublish-kernel/pull/1224 and https://github.com/ezsystems/ezplatform/pull/9
• ElasticSearch : https://github.com/ezsystems/ezpublish-kernel/tree/master/eZ/Publish/Core/Search/Elasticsearch/Content/Resources
• ElasticSearch Bundle commands : https://github.com/ezsystems/ezpublish-kernel/blob/master/eZ/Bundle/EzPublishSolrSearchEngineBundle/Command/SolrCreateIndexCommand.php
• Solr Bundle commands : https://github.com/ezsystems/ezpublish-kernel/blob/master/eZ/Bundle/EzPublishSolrSearchEngineBundle/Command/SolrCreateIndexCommand.php