[BUG] Some core plugin API documentations are missing

[bandinib-amzn]

Describe the bug

Some core plugin API documentations are missing

To Reproduce
Steps to reproduce the behavior:

1. Go to https://github.com/opensearch-project/OpenSearch-Dashboards/tree/main/src/core
2. Click on Core Public API, Core Server API, OpenSearch Dashboards Platform Plugin API
3. See Page not found error

Expected behavior
It should redirect to valid documentation.

OpenSearch Version
Please list the version of OpenSearch being used.

Dashboards Version
Please list the version of OpenSearch Dashboards being used.

Plugins

Please list all plugins currently enabled.

Screenshots

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Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Browser and version [e.g. 22]

Additional context

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[ashwin-pc]

Looks like these used to point to developer docs which we no longer have. But it might be worthwhile to point them to the public and server API report files in the meantime. They are not as easy to read as dedicated docsite links but will still be useful in the meantime while we get that up and running

[manasvinibs]

@ashwin-pc For OpenSearch Dashboards Platform Plugin API, do you think this is a good link to point to for now -https://github.com/opensearch-project/OpenSearch-Dashboards/blob/main/src/core/PRINCIPLES.md ?