Merge pull request auth0#147 from auth0/release/2.0.1

Merge pull request auth0#139 from auth0/patch/update-readme-for-v2.0.0

Update go get to v2 in README

Merge pull request auth0#135 from auth0/release/v2.0.0-beta.1

Add Changelog for v2.0.0-beta.1 pre-release

Merge pull request auth0#129 from auth0/major/v2.0.0-beta-update-go-mod

Update go modules to v2

Isolate example-only dependencies (auth0#94)

Update jwt-go to v4 to address CVE-2020-26160 (auth0#69)