Move projects to their proper place, add READMEs

[shcheklein]

• DVC repos into docs/dvc ... cc @jorgeorpinel (low priority) removed bc of Move projects to their proper place, add READMEs #34 (comment)
• github-issues cc @ykasimov @mnrozhkov do we still need it? Do you plan to do a blog post?
• fashion-mnist - remove if /when not used cc @jorgeorpinel @alex000kim @dberenbaum - I think it was part of the Get Started? May be not used anymore.
• mnist - the same - do we need it, where?

[dberenbaum]

I don't think that fashion-mnist is being used anywhere

Edit: same with mnist

[dberenbaum]

• DVC repos into docs/dvc ... cc @jorgeorpinel (low priority)

I looked into it as part of #35, but when I started looking through the docs, I was concerned that going from get-started/data.xml -> docs/dvc/get-started/data.xml or similar everywhere makes all the paths look too long.

[shcheklein]

Yes, @dberenbaum it makes sense. Yes, let's keep it simpler, removed the item.

[jorgeorpinel]

See #37.