Fixing includes

Author: ryanjbaxter

README.adoc

@@ -102,7 +102,7 @@ string like that.)
 
 == Building
 
-:jdkversion: 17
+:jdkversion: 1.8
 
 === Basic Compile and Test
 

docs/src/main/asciidoc/README.adoc

@@ -12,8 +12,8 @@ include::getting-started.adoc[]
 
 == Building
 
-include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/building.adoc[]
+include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/3.1.x/docs/src/main/asciidoc/building.adoc[]
 
 == Contributing
 
-include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/contributing.adoc[]
+include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/3.1.x/docs/src/main/asciidoc/contributing.adoc[]

docs/src/main/asciidoc/spring-cloud-function.adoc

@@ -16,7 +16,7 @@ Mark Fisher, Dave Syer, Oleg Zhurakousky, Anshul Mehra, Dan Dobrin
 
 include::_intro.adoc[]
 
-include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/docs/src/main/asciidoc/contributing-docs.adoc[]
+include::https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/3.1.x/docs/src/main/asciidoc/contributing-docs.adoc[]
 
 == Getting Started