META Make this the easiest way to try Gno

[moul]

This repository aims to help anyone try Gno in under five minutes.

We want it to be super minimal. It should contain just one small .gno file with Render and Set functions, along with comments or instructions in the Render section to explain how to use gnokey. There should be no publishing or extra folders; just the basics.

The README should clearly explain:

• How to install it (git clone; make install). The make install command should check if Go is installed; if not, it should provide a link to instructions on how to install Go.
• How to run gnodev (make dev). The make dev command should not install and call a binary but instead run go run github.com/..., so we don't have to worry about the $PATH. In the future, we can expect to install precompiled binaries without needing to install Go.
• How to open the browser and try live editing at (https://localhost:8888).
• Where to continue (https://docs.gno.land, https://github.com/gnolang/by-examples, https://github.com/gnolang/repo-template)

The Makefile should also be very simple; just enough to run locally and test (make dev, make test). There should be no advanced setup or CI beyond perhaps one simple test action.

In the future, we can link to a more advanced repository like template-gno-project. Here, we prioritize simplicity while utilizing as many good tools as possible, including advanced tests, several p/r actions, CI, etc.