* Added lenient flag for synonym-tokenfilter.
Relates to #30968
* added docs for synonym-graph-tokenfilter
-- Also made lenient final
-- changed from !lenient to lenient == false
* Changes after review (1)
-- Renamed to ElasticsearchSynonymParser
-- Added explanation for ElasticsearchSynonymParser::add method
-- Changed ElasticsearchSynonymParser::logger instance to static
* Added lenient option for WordnetSynonymParser
-- also added more documentation
* Added additional documentation
* Improved documentation