Add API Guides

[nhtruong]

(Spawn off of meta Issue: https://github.com/opensearch-project/opensearch-clients/issues/56) To help drive adoption of OpenSearch, and improve user's experience, we're working on adding more documentation for all clients. One of the strategies mentioned in said issue is writing a collection of articles serving as a User's Guide for each client. This issue will serve as a hub for all issues related to this topic.

Each Guide/Article will be a good-first-issue for new contributors to work on. There's already a Ruby version of each article that the articles on this repo should be based upon. Most of the time, we only need to replace the Ruby code blocks with the client code of this repo. Please refer to the meta issue for more details.

• [ ] https://github.com/opensearch-project/opensearch-net/issues/185
• [ ] https://github.com/opensearch-project/opensearch-net/issues/186
• [x] https://github.com/opensearch-project/opensearch-net/issues/187
• [x] https://github.com/opensearch-project/opensearch-net/issues/188
• [x] https://github.com/opensearch-project/opensearch-net/issues/189
• [x] https://github.com/opensearch-project/opensearch-net/issues/190

[Djcarrillo6]

Hi Thomas, when you have a moment I'd like to have this issue assigned to me. Thanks

[Xtansia]

@Djcarrillo6 Maybe comment on the issue for the specific guide you'd like to work on first, so that others can pick up other guides too if they want?

[Djcarrillo6]

For sure @Xtansia , I'd like to work on #187 first..

[Xtansia]

For sure @Xtansia , I'd like to work on #187 first..

@Djcarrillo6 sorry, you need to comment on #187 itself, due to the way Github works, I can't assign it to you unless you "participate" on that actual issue