Added blog "Setting Up Prometheus Alerts with Webex Integration"

[AkshayAwate]

Added new blog for "Prometheus Alerts with Webex Integration".

[AkshayAwate]

@RichiH would you review this PR ?

[jan--f]

Hello from the bug scrub!

This looks like a more appropriate post for a Webex blog, as this assumes the reader has an account.
@AkshayAwate Any thoughts on why this should be a Prometheus blog post?

[AkshayAwate]

Hi @jan--f ,

Thanks for the review!

My intention with this post was to demonstrate how Prometheus Alertmanager can be extended using webhooks for custom integrations. Webex is used as a concrete example, similar to how Slack or PagerDuty integrations are documented.

The focus of the post is on:
• Configuring Alertmanager receivers
• Using webhooks for custom notifications
• Grouping and formatting alerts

Webex is simply the notification medium in this example, and the webhook pattern can be adapted for other systems as well.

I’d be happy to adjust the introduction to clarify that the main goal is showcasing Prometheus and Alertmanager extensibility rather than Webex specifically.