[DOCS] Reformat ASCII folding token filter docs

[jrodewig]

Reformats the ASCII folding token filter docs:

• Adds a title abbreviation
• Updates the description with a short example and Lucene link
• Adds an analyze API example with resulting tokens
• Updates the example adding the token filter to an analyzer
• Updates the parameter docs and custom token filter example
• Updates the Lucene link in the apostrophe token filter docs

The configurable parameters and customize sections build on the template in the existing simple analyzer and apostrophe token filter docs.

I hope to re-use this format for other token filter docs. All feedback is welcome!

[elasticmachine]

Pinging @elastic/es-docs (>docs)

[elasticmachine]

Pinging @elastic/es-search (:Search/Analysis)

[debadair]

Left some editorial comments, but otherwise LGTM. I think the overall format works well.

[jrodewig]

Thanks @debadair.