README: add pkg.go.dev and github actions badges
-# Gonum [![Build Status](https://www.travis-ci.com/gonum/gonum.svg?branch=master)](https://www.travis-ci.com/gonum/gonum/branches) [![Build status](https://ci.appveyor.com/api/projects/status/valslkp8sr50eepn/branch/master?svg=true)](https://ci.appveyor.com/project/Gonum/gonum/branch/master) [![codecov.io](https://codecov.io/gh/gonum/gonum/branch/master/graph/badge.svg)](https://codecov.io/gh/gonum/gonum) [![coveralls.io](https://coveralls.io/repos/gonum/gonum/badge.svg?branch=master&service=github)](https://coveralls.io/github/gonum/gonum?branch=master) [![GoDoc](https://godoc.org/gonum.org/v1/gonum?status.svg)](https://godoc.org/gonum.org/v1/gonum) [![Go Report Card](https://goreportcard.com/badge/github.com/gonum/gonum)](https://goreportcard.com/report/github.com/gonum/gonum) [![stability-unstable](https://img.shields.io/badge/stability-unstable-yellow.svg)](https://github.com/emersion/stability-badges#unstable)
+# Gonum
+
+[![Build status](https://github.com/gonum/gonum/workflows/CI/badge.svg)](https://github.com/gonum/gonum/actions)
+[![Build Status](https://www.travis-ci.com/gonum/gonum.svg?branch=master)](https://www.travis-ci.com/gonum/gonum/branches)
+[![Build status](https://ci.appveyor.com/api/projects/status/valslkp8sr50eepn/branch/master?svg=true)](https://ci.appveyor.com/project/Gonum/gonum/branch/master)
+[![codecov.io](https://codecov.io/gh/gonum/gonum/branch/master/graph/badge.svg)](https://codecov.io/gh/gonum/gonum)
+[![coveralls.io](https://coveralls.io/repos/gonum/gonum/badge.svg?branch=master&service=github)](https://coveralls.io/github/gonum/gonum?branch=master)
+[![go.dev reference](https://pkg.go.dev/badge/gonum.org/v1/gonum)](https://pkg.go.dev/gonum.org/v1/gonum)
+[![GoDoc](https://godoc.org/gonum.org/v1/gonum?status.svg)](https://godoc.org/gonum.org/v1/gonum)
+[![Go Report Card](https://goreportcard.com/badge/github.com/gonum/gonum)](https://goreportcard.com/report/github.com/gonum/gonum)
+[![stability-unstable](https://img.shields.io/badge/stability-unstable-yellow.svg)](https://github.com/emersion/stability-badges#unstable)
## Installation
