This change adds a new plugin called `analysis-nori` that exposes
Korean text analysis in es using the new Lucene Korean analyzer module named (`nori`).
The plugin adds:
* a Korean analyzer: `nori`
* a Korean tokenizer: `nori_tokenizer`
* a part of speech stop filter: `nori_part_of_speech`
* a filter that can replace Hanja characters with their Hangul transcription: `nori_readingform`
* Centralised plugin docs in docs/plugins/
* Moved integrations into same docs
* Moved community clients into the clients section of the docs
* Removed docs/community
Closes#11734Closes#11724Closes#11636Closes#11635Closes#11632Closes#11630Closes#12046Closes#12438Closes#12579