docs: add snipsync lines

[lennessyy]

What was changed

• Added markers to allow snipsync to sync code snippets to docs.

Why?

• Sync code snippets to docs. These lines allow the documentation site to sync the code snippets to the docs, ensuring that the docs are updated along with the code samples in tested repositories.

Checklist

1. Closes N/A

2. How was this tested:

Clone the documentation repository. After yarn install, run yarn snipsync to fetch the code snippets. Review the copy destination to verify that the snippet was synced properly.

3. Any docs updates needed?

These snippets will be synced to https://docs.temporal.io/self-hosted-guide/visibility