Ensure that javadoc is generated in a full build

For reasons that I don’t understand, Maven has decided to stop running
the javadoc:jar task as part of the package phase. It appears to be
related to the addition of the build-helper plugin in
spring-boot-dependencies. Binding javadoc:jar to the prepare-package
phase convinces Maven to run it, apparently without any unwanted side
effects.

spring-boot-docs/pom.xml

@@ -335,6 +335,7 @@
 								<goals>
 									<goal>jar</goal>
 								</goals>
+								<phase>prepare-package</phase>
 								<configuration>
 									<includeDependencySources>true</includeDependencySources>
 									<dependencySourceIncludes>
@@ -383,7 +384,7 @@
 								</configuration>
 							</execution>
 							<execution>
-								<id>copy-versions-effective-pom</id>
+								<id>copy-dependencies-effective-pom</id>
 								<phase>generate-resources</phase>
 								<goals>
 									<goal>copy</goal>