add ngram overlap example selector

[hwchase17]

add example selector that picks based on ngram overlap

https://arxiv.org/abs/2212.02437

[dosubot]

Hi, @hwchase17. I'm helping the LangChain team manage their backlog and I wanted to let you know that we are marking this issue as stale. The issue you raised is a request to add an example selector that chooses examples based on ngram overlap. You provided a link to a relevant paper for reference. However, there hasn't been any activity or comments on the issue yet.

Could you please let us know if this issue is still relevant to the latest version of the LangChain repository? If you respond, the LangChain team will be notified to take a look. Otherwise, if we don't hear back from you, the issue will be automatically closed in 7 days. Thank you!