Reorganize and add comments to build.properties

build.properties

 version=3.1.0
-# osgi ranges
-spring.osgi.range.nq=${version:[=.=.=, =.=.+1)}
-spring.osgi.range="${spring.osgi.range.nq}"
-aj.osgi.range="[1.6.8, 2.0.0)"
 
-#
-release.type=integration
 natural.name=spring-framework
 project.name=Spring Framework
 project.key=SPR
@@ -17,14 +11,19 @@ javadoc.max.memory=1024M
 test.vm.args=-Xmx1024M -XX:MaxPermSize=512M -XX:+HeapDumpOnOutOfMemoryError
 compiler.args=-enableJavadoc -warn:none
 
-# For when releasing
+## common osgi ranges used in template.mf files
+spring.osgi.range.nq=${version:[=.=.=, =.=.+1)}
+spring.osgi.range="${spring.osgi.range.nq}"
+aj.osgi.range="[1.6.8, 2.0.0)"
+
+## For GA releases
 #release.type=release
 #build.stamp=RELEASE
 
-# For when releasing milestones
+## For milestone releases
 #release.type=milestone
 #build.stamp=M1
 
-# For development in trunk
-#release.type=integration
+## For trunk development / ci builds
+release.type=integration
 #build.stamp=BUILD-SNAPSHOT