docs: rework recording instructions with CYPRESS_RECORD_KEY

[MikeMcC399]

• supports resolution of issue Add documentation for migrating from CLI #1440

Situation

The README document contains several examples for recording to Cypress Cloud including:

• Record test results on Cypress Cloud
• Project ID and Record Key

There are several issues:

• The first example is incomplete and does not run because it is missing the CYPRESS_RECORD_KEY.
• In the Project ID and Record Key section, the comment about "typically" setting the recordKey as a CLI parameter is out-of-place, because the Cypress GitHub Action only uses CLI options exceptionally, not typically, and there is no equivalent action parameter to pass the CYPRESS_RECORD_KEY. It must be passed as an environment variable.
• Variable names used in the README are different from the ones used in .github/workflows/example-recording.yml

Not all recording examples contain the minimum of including a CYPRESS_RECORD_KEY environment variable.

Change

Merge the above two sections by combining the examples and removing the Project ID and Record Key header.

Align with terms on https://docs.cypress.io/cloud/account-management/projects for projectId and "record key".

Align the README example variable names with the ones used in .github/workflows/example-recording.yml

• EXAMPLE_PROJECT_ID
• EXAMPLE_RECORDING_KEY

Ensure that all recording examples include CYPRESS_RECORD_KEY for consistency.

[cypress-app-bot]

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[github-actions]

🎉 This PR is included in version 6.8.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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