docs: add note about supported environments (#1492)
docs: add note about supported environments (#1492)

Add a note in the Support Browsers section about being able to run when features are natively supported or polyfilled correctly.

Closes: #1136 

## Reviewer checks

**Required fields, to be filled out by PR reviewer(s)**
- [x] Follows the commit message policy, appropriate for next version
- [x] Has documentation updated, a DU ticket, or requires no documentation change
- [x] Includes new tests, or was unnecessary
- [x] Code is reviewed for security by: @jkodu 

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