chore: Update preview docs to refer to the main branch

[engedaam]

Fixes #N/A

Description

• The preview docs should reference the main branch as the is the branch where permission and API changes are pushed

How was this change tested?

• N/A

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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[coveralls]

Pull Request Test Coverage Report for Build 9960736448

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 79.099%

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Totals
Change from base Build 9960268431:	0.01%
Covered Lines:	5934
Relevant Lines:	7502

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💛 - Coveralls

[jmdeal]

LGTM 🚀