Add other badges too

Author: kwankyu

README.md

@@ -37,11 +37,13 @@ Table of Contents
 Getting Started
 ---------------
 
-Those who are impatient may use the Binder badge
+Those who are impatient may use prebuilt Sage available online from any of
 
-[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/sagemath/sage-binder-env/master)
+[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/sagemath/sage-binder-env/master
+)   [![Gitpod Ready-to-Code](https://img.shields.io/badge/Gitpod-Ready--to--Code-blue?logo=gitpod)](https://gitpod.io/#https://github.com/sagemath/sage/tree/master
+)   [![Open in GitHub Codespaces](https://img.shields.io/badge/Open_in_GitHub_Codespaces-black?logo=github)](https://codespaces.new/sagemath/sage/tree/master)
 
-to build and launch a Sage computing environment with no local installation. Otherwise read on.
+without local installation. Otherwise read on.
 
 The [Sage Installation Guide](https://doc.sagemath.org/html/en/installation/index.html)
 provides a decision tree that guides you to the type of installation