fix(guides): Add build and start at example of Cypress Docker Images

[wafuwafu13]

https://docs.cypress.io/guides/continuous-integration/github-actions#Testing-in-Chrome-and-Firefox-with-Cypress-Docker-Images

without build and start:

...
Cypress could not verify that this server is running:

  > http://localhost:3000

We are verifying this server because it has been configured as your baseUrl.

Cypress automatically waits until your server is accessible before running tests.

We will try connecting to it 3 more times...
We will try connecting to it 2 more times...
We will try connecting to it 1 more time...

Cypress failed to verify that your server is running.

Please start this server and then run Cypress again.
Test run failed, code 1
More information might be available above
Cypress module has returned the following error message:
Could not find Cypress test run results
Error: Could not find Cypress test run results

[netlify]

👷 Deploy request for cypress-docs pending review.
Visit the deploys page to approve it

🔨 Explore the source changes: c8940c5

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

wafuwafu13 seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[vercel]

@wafuwafu13 is attempting to deploy a commit to the Cypress Team on Vercel.

A member of the Team first needs to authorize it.

[MikeMcC399]

This is an outdated and obsolete PR.

The issue is already fixed and so the PR should be closed.