docs: Add test reporting doc to benchmarks dir

[stubbsta]

Description

This PR is a first pass at adding a nwaku test summary page which aims to provide a quick reference for anyone implementing the waku protocol using nwaku to see the expected performance as well as have quick access to test reports.

Changes

• Added file docs/benchmarks/test-results-summary.md

How to test

1. Pull https://github.com/waku-org/docs.waku.org
2. Edit url to use this branch: https://github.com/waku-org/docs.waku.org/blob/develop/fetch-content.js#L64
3. yarn build
4. yarn serve

[stubbsta]

This is a draft to get inputs on the formatting and content.
The Quick ref section definitely needs work. I would appreciate some info on how to relate the data back to Status App.

[jm-clius]

Thanks for this! I've added a couple of comments and suggestions on what other sections to add.

[stubbsta]

@fryorcraken I wonder if the TL;DR section is not too wordy? Is the requirement not to have it be something very short that can be read quickly and easily remembered such as:

• Relay network average bandwidth usage: x KB/s
• Disv5 average bandwidth usage: y KB/s
• etc.

and then if the reader wants more info (such as the network size and message rate for the simulations where the above values were obtained, they can look at the Insights section and if they want even more info they can go look at the reports on notion?