[Guide] Snapshot API

[saimedhi]

What is the bug?

Create guides/snapshot.md similar to the Ruby guide

What is the expected outcome?

The guide 'snapshot.md' need to have example codes for different snapshot operations.

All code-blocks, when run from start to finish in order they appear in the guide, do not throw any errors. If you want to demonstrate that certain statements will throw errors, they must be wrapped in a try/catch and print out the expected error. All code-blocks are properly marked with the language it's written in (i.e. ```python)

For additional references on how to format guide, please refer existing guides in opensearch-py repo.

[saimedhi]

Please feel free to take up this issue and raise a PR with your proposed solution.

[roma2023]

Can I please take up this issue?