This change removes the Lucene's experimental flag from the documentations of the following
tokenizer/filters:
* Simple Pattern Split Tokenizer
* Simple Pattern tokenizer
* Flatten Graph Token Filter
* Word Delimiter Graph Token Filter
The flag is still present in Lucene codebase but we're fully supporting these tokenizers/filters
in ES for a long time now so the docs flag is misleading.
Co-authored-by: James Rodewig <james.rodewig@elastic.co>