Fix typo (Section 5.2 -> Section 5.1)

Comment From: pivotal-cla

@joshua-qa Please sign the Contributor License Agreement!

Click here to manually synchronize the status of this Pull Request.

See the FAQ for frequently asked questions.

Comment From: pivotal-cla

@joshua-qa Thank you for signing the Contributor License Agreement!

Comment From: snicoll

@joshua-qa thank you for making your first contribution to Spring Framework.