Add starter entry for Azure Application Insights

Closes gh-15628

Author: izeye

spring-boot-project/spring-boot-starters/README.adoc

@@ -43,6 +43,9 @@ do as they were designed before this was clarified.
 | https://azure.microsoft.com/[Azure]
 | https://github.com/Microsoft/azure-spring-boot-starters
 
+| https://docs.microsoft.com/en-us/azure/application-insights/app-insights-overview[Azure Application Insights]
+| https://github.com/Microsoft/ApplicationInsights-Java/tree/master/azure-application-insights-spring-boot-starter
+
 | https://github.com/vladimir-bukhtoyarov/bucket4j/[Bucket4j]
 | https://github.com/MarcGiffing/bucket4j-spring-boot-starter