docs: add small documentation and navigation changes to README

[mfts]

[what-the-diff[bot]]

• Added a new section to the README.md file
• Changed the title of this repository from "tea" to "cli".
• Updated all links in the readme that pointed at tea/core and changed them to point at pantry.* repositories instead, as well as added some additional information about those repos (see above).

[mxcl]

I think these changes are sensible, though we should work on it a bit.

One issue with them is tea requires the first header to contain the version so we can extract it. Perhaps this is bad? But it's the case and we'd need to change the code if we were going to keep this structure.

Also tea is not a package manager is like a thing I like :)

[mxcl]

https://github.com/mfts/tea-cli/tree/docs/improvements <-- to see changes