Configure bootJar task to add documentation to Spring Boot fat jar

Closes gh-521

samples/junit5/build.gradle

@@ -58,7 +58,7 @@ asciidoctor {
 	dependsOn test
 }
 
-jar {
+bootJar {
 	dependsOn asciidoctor
 	from ("${asciidoctor.outputDir}/html5") {
 		into 'static/docs'

samples/rest-assured/build.gradle

@@ -50,7 +50,7 @@ asciidoctor {
 	dependsOn test
 }
 
-jar {
+bootJar {
 	dependsOn asciidoctor
 	from ("${asciidoctor.outputDir}/html5") {
 		into 'static/docs'

samples/rest-notes-spring-hateoas/build.gradle

@@ -56,7 +56,7 @@ asciidoctor {
 	dependsOn test
 }
 
-jar {
+bootJar {
 	dependsOn asciidoctor
 	from ("${asciidoctor.outputDir}/html5") {
 		into 'static/docs'

samples/testng/build.gradle

@@ -55,7 +55,7 @@ asciidoctor {
 	dependsOn test
 }
 
-jar {
+bootJar {
 	dependsOn asciidoctor
 	from ("${asciidoctor.outputDir}/html5") {
 		into 'static/docs'