Fix version of Spring Framework in doc

Closes gh-5415

spring-boot-docs/pom.xml

@@ -739,6 +739,7 @@
 									<doctype>book</doctype>
 									<attributes>
 										<docinfo>true</docinfo>
+										<spring-version>${spring.version}</spring-version>
 										<spring-boot-version>${project.version}</spring-boot-version>
 										<spring-boot-docs-version>${project.version}</spring-boot-docs-version>
 										<spring-boot-repo>${spring-boot-repo}</spring-boot-repo>

spring-boot-docs/src/main/asciidoc/getting-started.adoc

@@ -37,7 +37,7 @@ diverge from the defaults.
 [[getting-started-system-requirements]]
 == System Requirements
 By default, Spring Boot {spring-boot-version} requires http://www.java.com[Java 7] and
-Spring Framework 4.1.5 or above. You can use Spring Boot with Java 6 with some additional
+Spring Framework {spring-version} or above. You can use Spring Boot with Java 6 with some additional
 configuration. See <<howto.adoc#howto-use-java-6>> for more details. Explicit build support
 is provided for Maven (3.2+) and Gradle (1.12+).