Deprecate in favor of JSON.jl

[jakobjpeters]

From Slack, I see that this package is deprecated in favor of JSON.jl v1.0 (congrats on the release!). Let's document this in README.md?

[DilumAluthge]

From Slack, I see that this package is deprecated in favor of JSON.jl v1.0 (congrats on the release!). Let's document this in README.md?

Technically, some users will need to keep using JSON3.jl for the time being:

If you rely heavily on this feature, continue using JSON3.jl for this specific purpose until this functionality is migrated to a separate package

[Source]