Fix link to Go! (2003 language by Francis McCabe)

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### Fix link to Go! (2003 language by Francis McCabe)

I forgot to fix the link to the Go! programming language. It displays as an anchor link to a non-existent section, while it should point to another repository. I just don't feel like fixing it today.

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https://github.com/seanpm2001/Learn-GoogleGo/issues/2

