Rename Transformer to ResourceTransformer

Aims to better align with the name of [org.apache.maven.plugins.shade.resource.ResourceTransformer.java](https://github.com/apache/maven-shade-plugin/blob/master/src/main/java/org/apache/maven/plugins/shade/resource/ResourceTransformer.java) and to distinguish itself from [org.gradle.api.Transformer.java](https://docs.gradle.org/current/javadoc/org/gradle/api/Transformer.html).

Author: Goooler

src/docs/changes/README.md

@@ -10,7 +10,8 @@
 
 **Changed**
 
-- **BREAKING CHANGE:** Rename `Transformer` to `ResourceTransformer`. ([#1288](https://github.com/GradleUp/shadow/pull/1288))
+- **BREAKING CHANGE:** Rename `Transformer` to `ResourceTransformer`. ([#1288](https://github.com/GradleUp/shadow/pull/1288))  
+  Aims to better align with the name of [org.apache.maven.plugins.shade.resource.ResourceTransformer.java](https://github.com/apache/maven-shade-plugin/blob/master/src/main/java/org/apache/maven/plugins/shade/resource/ResourceTransformer.java) and to distinguish itself from [org.gradle.api.Transformer.java](https://docs.gradle.org/current/javadoc/org/gradle/api/Transformer.html).
 
 **Fixed**