Clearer when-to-register criteria

[Rratic]

Here's the original comment:

itsdfish/JokerJailBreak.jl#1 (comment)

I don't know how many packages have sneaked in the registery, but it could be necessary, I guess.

[DilumAluthge]

Here is what the General registry README currently says:

General/README.md

Lines 93 to 122 in aedbcb2

	### Should I register my package now?
	If your package is at a stage where it might be useful to others, or provide functionality other
	packages in General might want to rely on, go for it!
	We ask that you consider the following best practices.
	* It is easier for others to use your package if it has **documentation** that explains
	what the package is for and how to use it. This could be in the form of a README
	or hosted documentation such as that generated by
	[Documenter.jl](https://github.com/JuliaDocs/Documenter.jl).
	* And in order to provide reliable functionality for your users, it is also important
	to setup **tests** (see
	[the Pkg.jl docs](https://pkgdocs.julialang.org/v1/creating-packages/#Adding-tests-to-the-package)
	and the [Test stdlib docs](https://docs.julialang.org/en/v1/stdlib/Test/)), which
	can be automatically run by free **continuous integration** services such as GitHub Actions. As part of the test suite, tools like [Aqua.jl](https://github.com/JuliaTesting/Aqua.jl) and [JET.jl](https://github.com/aviatesk/JET.jl) can help you remove bugs or typos and improve the general quality of your code.
	Packages like [PkgTemplates.jl](https://github.com/invenia/PkgTemplates.jl) or
	[PkgSkeleton.jl](https://github.com/tpapp/PkgSkeleton.jl) provide easy ways to setup
	documentation, tests, and continuous integration.
	Some types of packages should not be registered, or are not yet ready for registration:
	* The General registry is not a place for "personal packages" that consist of
	collections of "utility functions" nor for packages that are only useful for a closed group
	(like a research group or a company). For that, it is easy to set up your own registry using
	for example [LocalRegistry.jl](https://github.com/GunnarFarneback/LocalRegistry.jl). The
	[Pkg documentation about registries](https://pkgdocs.julialang.org/v1/registries/) might be useful
	if you decide to go this route.
	* "Empty" packages that do not yet have functionality are not ready to be registered.

I think this covers your question, right? Are there specific questions that you have that are not answered by the above? Or specific information that you'd like us to add to the README?