chore(egen): follows new template, fixes typos, K80-->T4, REGION-->LO…

…CATION etc. (#3214)

* chore: follows new template, fixes typos, removes unnecessary code-highlights, replaces K80 with T4, replaces REGION with LOCATION, removes IS_TESTING in cleaning up section, makes sentence/heading corrections and re-organizes some subsections as per the tutorial

* chore, refactor: minor markdown corrections, updates machine_type description and code to suit the explanation

* chore: addresses review comments and corrects 'uploading to a Vertex AI model resource' to 'uploading to Vertex AI Model Registry'

* chore: addresses the review comments

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Co-authored-by: krishr2d2 <krishna.movva@egen.ai>