GLOSSARY.md: Small typo in Generative AI glossary entry.

[nikunj8866]

I noticed a small typo in the GLOSSARY.md file.

In the Generative AI entry it currently says:

Overaching term describing AI models that generate content as requested in a prompt.

The word "Overaching" should be "Overarching".

Overarching term describing AI models that generate content as requested in a prompt.

[felixarntz]

Fixed by #87