README.md: point to GitHub Actions instead of Travis

Also fix a typo and change a link from http to https

Author: fingolfin

README.md

@@ -2,11 +2,11 @@
 
 [![](https://img.shields.io/badge/docs-dev-blue.svg)](https://fluxml.github.io/MacroTools.jl/dev)
 [![](https://img.shields.io/badge/docs-stable-blue.svg)](https://fluxml.github.io/MacroTools.jl/stable)
-[![Build Status](https://travis-ci.org/FluxML/MacroTools.jl.svg?branch=master)](https://travis-ci.org/FluxML/MacroTools.jl)
+[![Build Status](https://github.com/FluxML/MacroTools.jl/actions/workflows/CI.yml/badge.svg)](https://github.com/FluxML/MacroTools.jl/actions/workflows/CI.yml)
 
-MacroTools provides a library of tools for working with Julia code and expressions. This includes a powerful template-matching system and code-walking tools that let you do deep transformations of code in a few lines. See the [docs](http://fluxml.github.io/MacroTools.jl/) for more info.
+MacroTools provides a library of tools for working with Julia code and expressions. This includes a powerful template-matching system and code-walking tools that let you do deep transformations of code in a few lines. See the [docs](https://fluxml.github.io/MacroTools.jl/) for more info.
 
-Suggestions, issues and pull requsts are welcome.
+Suggestions, issues and pull requests are welcome.
 
 ## Installation