[DOC] Introduce ReadFromScratchPads and WriteToScratchPadsTools

[mingshl]

What do you want to do?

• Request a change to existing documentation
• [x ] Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request.

[DOC] Introduce ReadFromScratchPads and WriteToScratchPadsTools

Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
3.3
What other resources are available? Provide links to related issues, POCs, steps for testing, etc.
resolves opensearch-project/ml-commons#4192

[opensearch-ci-bot]

Hi @mingshl
,

As part of the entrance criteria, all the documentation pull requests need to be drafted and in technical review.

Since there is no pull request linked to this issue, please take one of the following actions:

• Create the pull request and link it to this issue.
  
• If you already have a pull request created, please link it to this issue.
  
• If this feature is not targeted for the currently labeled release version, please update the issue with the correct release version.
  

Please note: Missing documentation can block the release and cause delays in the overall process.

Thank you!

[opensearch-ci-bot]

Hi @mingshl
,

As part of the entrance criteria, all the documentation pull requests need to be drafted and in technical review.

Since there is no pull request linked to this issue, please take one of the following actions:

• Create the pull request and link it to this issue.
  
• If you already have a pull request created, please link it to this issue.
  
• If this feature is not targeted for the currently labeled release version, please update the issue with the correct release version.
  

Please note: Missing documentation can block the release and cause delays in the overall process.

Thank you!