Fix documentation links

Closes gh-1627

USING.adoc

@@ -1,4 +1,3 @@
-:spring-boot-docs: https://docs.spring.io/spring-boot/docs/current/reference/html
 = User Guide
 
 If you're wondering how to use https://start.spring.io or what features are available,
@@ -190,7 +189,7 @@ Refer to the documentation of your favorite IDE for more details.
 The `spring` command line tool defines an `init` command that allows you to create a
 project using Spring Initializr. It defaults to start.spring.io.
 
-Check {spring-boot-docs}/spring-boot-cli.html#cli-init[the documentation for more details].
+Check https://docs.spring.io/spring-boot/cli/index.html[the documentation for more details].
 
 
 

start-site/src/main/java/io/spring/start/site/extension/code/kotlin/KotlinCoroutinesCustomizer.java

@@ -61,7 +61,7 @@ public void customize(HelpDocument document, Build build) {
 			String frameworkVersion = resolve.get("org.springframework:spring-core");
 			String versionToUse = (frameworkVersion != null) ? frameworkVersion : "current";
 			String href = String.format(
-					"https://docs.spring.io/spring/docs/%s/spring-framework-reference/languages.html#coroutines",
+					"https://docs.spring.io/spring-framework/reference/%s/languages/kotlin/coroutines.html",
 					versionToUse);
 			document.gettingStarted()
 				.addReferenceDocLink(href, "Coroutines section of the Spring Framework Documentation");