Correct minor typo in error message - 'experiement'

[gemmakbarlow]

Summary

• Noticed this printing to our console earlier today; typo now corrected.

Test plan

• Confirming everything builds & passes on CI should be sufficient here

Issues

• N / A

[jaeopt]

@gemmakbarlow Thanks for your contribution. If not done yet, can you sign our CLA?
https://github.com/optimizely/swift-sdk/blob/master/CONTRIBUTING.md

[gemmakbarlow]

@gemmakbarlow Thanks for your contribution. If not done yet, can you sign our CLA? https://github.com/optimizely/swift-sdk/blob/master/CONTRIBUTING.md

Thanks for the flag @jaeopt; CLA now completed ✅

[gemmakbarlow]

@gemmakbarlow Thanks for your contribution. If not done yet, can you sign our CLA? https://github.com/optimizely/swift-sdk/blob/master/CONTRIBUTING.md

Thanks for the flag @jaeopt; CLA now completed ✅

I see I've got a few other things to tidy-up to match the guidelines; will do that shortly.

[jaeopt]

LGTM