add & update CI badges

Author: keiji

README.md

@@ -1,6 +1,6 @@
 # COVID-19 Contact-Confirming Application COCOA (English)/([Japanese](README.ja.md))
 
-[![CI](https://github.com/cocoa-mhlw/cocoa/actions/workflows/CI.yml/badge.svg?branch=master)](https://github.com/cocoa-mhlw/cocoa/actions/workflows/CI.yml)
+[![App develop](https://github.com/cocoa-mhlw/cocoa/actions/workflows/CI.yml/badge.svg?branch=develop)](https://github.com/cocoa-mhlw/cocoa/actions/workflows/CI.yml)
 
 This is the official repository for the COVID-19 Contact-Confirming Application(COCOA).  
 COCOA has been developed from [Project Covid19Radar](https://github.com/Covid-19Radar).