Added Introduction section

[mstcyr2]

Adding introduction section to astroquery.mast docs.

[codecov]

Codecov Report

Merging #2725 (dca6af1) into main (7277870) will increase coverage by 0.00%.
The diff coverage is n/a.

❗ Current head dca6af1 differs from pull request most recent head c03b91d. Consider uploading reports for the commit c03b91d to get more accurate results

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[bsipocz]

@jaymedina - If you and Makayla are up for it, this maybe an easy PR to practice squashing.

[jaymedina]

Looks good! I'd like to see the intro section beefed up a little bit more. Maybe briefly talk about the 3 different services offered: Observations (observations.py), Catalogs (cutouts.py) and Cutouts (cutouts.py) and give a quick overview of their purpose based on what you read about them in the documentation. I'd also like to read a little bit more about MAST and what it offers to the astro community. You can use resources like this to help form your statements.

[jaymedina]

Looks good

[mstcyr2]

@bsipocz I think this is ready to merge, do I need to rebase?

[bsipocz]

Look all good @mstcyr2, thank you!

[bsipocz]

@mstcyr2 - I don't see a conflict, nor a code that could actually fail, so no need to rebase. Thanks for the squash and iterations!