Remove Push Notification documentation

[niravcodes]

Documentation Update Pull Request

Description

We aren't handling all the push notification stuff anymore. We will just forward notification invites to a websock endpoint or a webhook and let customers handle it themselves.

This PR removes mention of the Push Notification system we previously had to avoid confusing customers.

Type of Change

• New documentation
• Update to existing documentation

Documentation Change Details

• Changes Summary: Brief summary of the changes

Motivation and Context

Why is this change required? What problem does it solve?

Checklist:

• My documentation follows the style guidelines of this project
• I have performed a self-review of my documentation
• My changes generate no new warnings
• Builds successfully locally

Additional Notes

Add any other context about the documentation update here.

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