[Docs] improvement request for quote_char setting

[dharada]

This is not feature request, but Docs improvement request form a user.

• Version: 3.0.10

Findings

If we set "\"" to quote_char, then we would get error such as "Error parsing csv { ・・・・・ :exception=>#<ArgumentError: :quote_char has to be a single character String>}".

https://www.elastic.co/guide/en/logstash/current/plugins-filters-csv.html#plugins-filters-csv-quote_char

If we want to set as above, it seems we should set config.support_escapes as true in lostash.yml file. (default is false)

config.support_escapes: true
https://www.elastic.co/guide/en/logstash/current/logstash-settings-file.html

Request

Could you consider to add a description about config.support_escapes for quote_char setting ? if this makes documents more understandable/useful.