[README] add documentation about CW_ELASTICSEARCH_SSL_SHOW_WARN

README.rst

@@ -9,6 +9,7 @@ Parameters
 * elasticsearch-locations (CW_ELASTICSEARCH_LOCATIONS)
 * index-name (CW_INDEX_NAME)
 * elasticsearch-verify-certs (CW_ELASTICSEARCH_VERIFY_CERTS)
+* elasticsearch-ssl-show-warn (CW_ELASTICSEARCH_SSL_SHOW_WARN)
 
 Pyramid debug panel
 ~~~~~~~~~~~~~~~~~~~
@@ -32,4 +33,15 @@ panel in your ``pyramid.ini``:
 
 The `cubicweb_elasticsearch.search_helpers.compose_search` referencies
 a custom `alltext` field which contains all indexed text. This field  must be
-defined in the custom Indexer mapping.
\ No newline at end of file
+defined in the custom Indexer mapping.
+
+HTTPS and SSL certificates in communication with server
+-------------------------------------------------------
+
+In some cases (ElasticSearch Kubernetes deployment for example), self signed
+certificates are used and can be ignored using elasticsearc-verify-certs, in
+this case, the python binding will issue warnings for each request, which is
+cumbersome when running requests in a `ccplugin` command. You can use
+`elasticsearch-ssl-show-warn (CW_ELASTICSEARCH_SSL_SHOW_WARN)` to remove
+those warnings (default is to show them). Most of the time, a better solution
+is to have proper certificates to authenticate the servers you are talking to.