Fix branches in adapter docs.

Resolves #401

README.adoc

@@ -4,7 +4,9 @@ Manual changes to this file will be lost when it is generated again.
 Edit the files in the src/main/asciidoc/ directory instead.
 ////
 
-image::https://travis-ci.org/spring-cloud/spring-cloud-function.svg?branch=master[Build Status, link=https://travis-ci.org/spring-cloud/spring-cloud-function]
+:branch: master
+
+image::https://travis-ci.org/spring-cloud/spring-cloud-function.svg?branch={branch}[Build Status, link=https://travis-ci.org/spring-cloud/spring-cloud-function]
 
 == Introduction
 

docs/src/main/asciidoc/README.adoc

@@ -1,4 +1,6 @@
-image::https://travis-ci.org/spring-cloud/spring-cloud-function.svg?branch=master[Build Status, link=https://travis-ci.org/spring-cloud/spring-cloud-function]
+:branch: master
+
+image::https://travis-ci.org/spring-cloud/spring-cloud-function.svg?branch={branch}[Build Status, link=https://travis-ci.org/spring-cloud/spring-cloud-function]
 
 == Introduction
 

docs/src/main/asciidoc/adapters/aws-intro.adoc

@@ -1,3 +1,5 @@
+:branch: master
+
 === AWS Lambda
 
 The https://aws.amazon.com/[AWS] adapter takes a Spring Cloud Function app and converts it to a form that can run in AWS Lambda.

docs/src/main/asciidoc/adapters/azure-intro.adoc

@@ -1,3 +1,5 @@
+:branch: master
+
 === Microsoft Azure
 
 The https://azure.microsoft.com[Azure] adapter bootstraps a Spring Cloud Function context and channels function calls from the Azure framework into the user functions, using Spring Boot configuration where necessary. Azure Functions has quite a unique, but invasive programming model, involving annotations in user code that are specific to the platform. The easiest way to use it with Spring Cloud is to extend a base class and write a method in it with the `@FunctionName` annotation which delegates to a base class method.

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

@@ -10,6 +10,7 @@ Mark Fisher, Dave Syer, Oleg Zhurakousky, Anshul Mehra
 :githubmaster: {github}/tree/master
 :docslink: {githubmaster}/docs/src/main/asciidoc
 :nofooter:
+:branch: master
 
 == Introduction
 
@@ -367,11 +368,11 @@ MESSAGE-9
 As well as being able to run as a standalone process, a Spring Cloud
 Function application can be adapted to run one of the existing
 serverless platforms. In the project there are adapters for
-https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-aws[AWS
+https://github.com/spring-cloud/spring-cloud-function/tree/{branch}/spring-cloud-function-adapters/spring-cloud-function-adapter-aws[AWS
 Lambda],
-https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-azure[Azure],
+https://github.com/spring-cloud/spring-cloud-function/tree/{branch}/spring-cloud-function-adapters/spring-cloud-function-adapter-azure[Azure],
 and
-https://github.com/spring-cloud/spring-cloud-function/tree/master/spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk[Apache
+https://github.com/spring-cloud/spring-cloud-function/tree/{branch}/spring-cloud-function-adapters/spring-cloud-function-adapter-openwhisk[Apache
 OpenWhisk]. The https://github.com/fnproject/fn[Oracle Fn platform]
 has its own Spring Cloud Function adapter. And
 https://projectriff.io[Riff] supports Java functions and its