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.

[RamanaReddy8801]

Hi @metal-messiah, could you please make the review changes.

1. Is it possible to add alerts to this quickstart? It's considered best practice.
2. I noticed that the dashboard chart titles are not in sentence case. It's recommended to use sentence case for them, e.g., Average Duration should be `Average duration.

[sjyothi54]

LGTM

[pkudikyala]

Hi @metal-messiah, Could you please address the following comments and implement the same changes in this pull request as well?
https://github.com/newrelic/newrelic-quickstarts/pull/2618/files#diff-ea46786b6683ec057ebefa607433a49265ebfe9f04076175a0dc1546042c9fa3

[metal-messiah]

Hi @RamanaReddy8801, @pkudikyala

I have applied the name changes in the dashboard JSON. As far as alerts, we have not established common criteria to alert on for this dataset.