update README

Author: jenschude

README.md

@@ -166,7 +166,9 @@ The latest stable SDK release can be retrieved from [jcenter](https://bintray.co
 
 ```gradle
 ext {
-    sdkVersion = "0.3.1"
+    versions = [
+        commercetools: "0.3.1"
+    ]
 }
 
 sourceCompatibility = 1.8
@@ -176,9 +178,9 @@ repositories {
 }
 
 dependencies {
-    implementation 'com.commercetools.sdk:commercetools-sdk-java-api:${sdkVersion}'
-    implementation 'com.commercetools.sdk:commercetools-sdk-java-importapi:${sdkVersion}'
-    implementation 'com.commercetools.sdk:commercetools-sdk-java-ml:${sdkVersion}'
+    implementation "com.commercetools.sdk:commercetools-sdk-java-api:${versions.commercetools}"
+    implementation "com.commercetools.sdk:commercetools-sdk-java-importapi:${versions.commercetools}"
+    implementation "com.commercetools.sdk:commercetools-sdk-java-ml:${versions.commercetools}"
 }
 ```
 ```maven

build.gradle

@@ -61,7 +61,7 @@ class Version {
 
 tasks.register("writeVersionToReadme") {
     doLast {
-        ant.replaceregexp(match: 'sdkVersion = \"[^\\s]+\"', replace: "sdkVersion = \"${globalVersion}\"", flags:'g', byline:true) {
+        ant.replaceregexp(match: 'commercetools: \"[^\\s]+\"', replace: "commercetools: \"${globalVersion}\"", flags:'g', byline:true) {
             fileset(dir: projectDir, includes: 'README.md')
         }
         ant.replaceregexp(match: '<commercetools.version>.+</commercetools.version>', replace: "<commercetools.version>${globalVersion}</commercetools.version>", flags:'g', byline:true) {