Fix 'default typecheck mode'

[ishtar112]

Changes

Updates the typechecking docs to appropriately reflect the default typechecking mode for scripts (currently nocheck but documented as nonstrict).

Evidence [that the default mode is nocheck]

• There is an open Studio beta to use nonstrict as the default.
• Simply comparing the differences between how a script is typechecked in both nocheck and nonstrict will show that [without enabling the Studio beta] scripts default to nocheck.
• A member of the Luau team asserting that the default is nocheck.

Additional Notes

The Luau docs do happen to say that nonstrict is the default. This seems to be the case for everywhere that isn't ROBLOX Studio. I'm assuming that someone [understandably] copied the Luau docs, which [unfortunately] isn't accurate for Studio.

[github-actions]

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[vegorov-rbx]

This change might have been appropriate before, but now it goes against what we have planned for Luau typechecking.

nocheck will not be the default. It's not even the default to people with non-strict by default Beta enabled or auto-enrolled.

Resolved by removing mention of default.

[IgnisRBX]

I opted to just remove mention of what's the default entirely, as it may adapt over time and become misleading if not updated frequently. This route simply states the options and lets scripters decide what to use.