SpringBoot Update configuration metadata appendix to remove description for Gradle 4.5 and earlier as it is no longer supported

Updating documentation to address issue #23245

Comment From: pivotal-issuemaster

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Comment From: pivotal-issuemaster

@ketaki-t Thank you for signing the Contributor License Agreement!

Comment From: mbhave

@ketaki-t Thank you for your first contribution to Spring Boot! This has now been merged into 2.2.x, 2.3.x and master.