Revise gpython 'About'?

@sbinet @ncw and anyone interested...

Currently, gpython's 'About' line on github is:

> gpython is a python interpreter written in go "batteries not included"

After the [upcoming worklist](https://github.com/go-python/gpython/issues/166), I think it would be good time to consider shifting this project's tagline to something that speaks to its strengths and how it offers value now and future forward. I see gpython as a leading choice for a Go developers looking for an interpreter to embed for real-world use -- especially if their "customers" tend to be non-professional developers, such as scientists.

Some ideas that seem in the right direction...

> gpython is a Python interpreter written in Go, \
> offering concurrent execution and new ways to (offer|deploy|use) your Go packages

> gpython is a Go-based Python interpreter consistent with Go concurrency, \
> offering new ways to (offer|deploy|use) your Go packages

And is it "Python" or "python", I can never know. Proper noun right? I definitely like "Go" over "go" when writing it in sentences to humans, so I'm inclined to be consistent with referring to Python. Or maybe there is _Python_ the language but there is _python_ code. I would love for someone to lmk to put my squirrel brain to rest on this. 🐿️

Drew