Change doma-processor version in README

Author: backpaper0

README.md

@@ -23,7 +23,7 @@ Spring Boot Support for [Doma](https://github.com/domaframework/doma)
 <dependency>
     <groupId>org.seasar.doma</groupId>
     <artifactId>doma-processor</artifactId>
-    <version>3.5.1</version>
+    <version>3.6.0</version>
     <optional>true</optional>
 </dependency>
 ```

how-to-release.md

@@ -18,6 +18,8 @@ The following example shows the command to update the description from 1.3.0 to
 sed -i '' -e 's/1\.3\.0/1\.4\.0/g' README.md
 ```
 
+And change `doma-processor` version.
+
 ## Set a new version
 
 Update pom.xml by Maven Versions Plugin.