Small update to wording in using-the-public-folder.md

[zanemayo]

I think I have corrected the wording.

I changed from 'Missing files will not be called at compilation time' to 'Missing files will not be caught at compilation time'.

If 'called' was indeed the intended wording, then please decline the PR without comment. I don't want to waste anyone's time.

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[stale]

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