[8.1] docs: 8.0 release notes and breaking changes (backport #7202)

[mergify]

This is an automatic backport of pull request #7202 done by Mergify.

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💔 Build Failed

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• Start Time: 2022-02-09T16:36:20.258+0000

• Duration: 68 min 29 sec

Test stats 🧪

Test	Results
Failed	0
Passed	4362
Skipped	14
Total	4376

Steps errors

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Restore files previously stashed

• Took 3 min 58 sec . View more details here
• Description: source

Checks if running on a Unix-like node

• Took 0 min 0 sec . View more details here

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