Release note tracker for v2.0.0

[mauriciopoppe]

I'll keep updating this description with notable changes coming in v2.0.0

• default output is a JS module (forces a major bump)
• added support for NextJS
• [new] renderer with web workers
• [new] register new graph types
• remove implicit support for mathjs
• different entrypoint in gh-pages depending on the version https://github.com/mauriciopoppe/function-plot/issues/279
• [API Design] Refactor option grid to be in the axis objects #299