Typo in filename & NGram Filter TokenChars query 

NGram Filter TokenChars query (Unknown if required) @Mpdreamz 

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/analysis-ngram-tokenfilter.html doesnt display the token_chars as an option but it's used in various articles and tracked in various queries on stackoverflow

* http://stackoverflow.com/questions/23374176/c-sharp-nest-elasticsearch-not-able-to-map-token-chars-to-nest-fluentmapping
* http://blog.qbox.io/multi-field-partial-word-autocomplete-in-elasticsearch-using-ngrams

Full copy of raw query being pushed in the article above here https://gist.github.com/ChrisMcKee/c4cab45080e52e35190a#file-elasticsearch-ngram-tokenchar-poc

Resulting mapping here https://gist.github.com/ChrisMcKee/c4cab45080e52e35190a#file-elasticsearch-ngram-tokenchar-poc-resultant-mapping

Obviously the tokenizer http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/analysis-ngram-tokenizer.html#analysis-ngram-tokenizer has it, so this may simply be a case of a common misunderstanding that ES seems to allow/maps in?

```
analysis: {
    filter: {
        nGram_filter: {
            max_gram: 20,
            min_gram: 2,
            type: nGramtoken_chars: [
                letter,
                digit,
                punctuation,
                symbol
            ]
        }
    }
```
Seems right though, luckily Martijn you have the advantage of being able to ask :)