feat: Add quickstart for browser page resources

[metal-messiah]

Summary

This PR adds a quickstart dashboard and installation instructions for new data collected by the browser agent - browser page resources.

Pre merge checklist

• Did you check you NRQL syntax? - Does it work?
• Did you include a Data source and Documentation reference?
• Are all documentation links publicly accessible?
• Did you check your descriptive content for voice and tone?
• Did you check your descriptive content for spelling and grammar errors?
• Did you review your content with a subject matter expert? (e.g. a Browser agent quickstart is reviewed with a member of the Browser Agent team)

Dashboards

• Does the PR contain a screenshot for each of your dashboards?
• Do your screenshots show data?
• Has the sanitization script been run on each dashboard?

[CLAassistant]

All committers have signed the CLA.

[github-actions]

The PR checks have run and found the following warnings:

Warning	Filepath
"permissions" field should not be used	dashboards/browser-page-resources/browser-page-resources.json

Reference the Contributing Docs for Dashboards for more information.