Put back docs as part of the build

Author: fmbenhassine

settings.gradle

@@ -76,6 +76,8 @@ include 'spring-statemachine-data:jpa'
 include 'spring-statemachine-data:redis'
 include 'spring-statemachine-data:mongodb'
 
+include 'docs'
+
 rootProject.children.each { project ->
 	if (project.name == 'spring-statemachine-data') {
         project.name = 'spring-statemachine-data-common'