BATCH-2192: Update versions of STS on the Getting Started Guide

* README.md updated as well for version.
* SpringSource Tool Suite also renamed to Spring Tool Suite to match product page.
BATCH-2201: Update URL's to point to spring.io in docs

Update URLs pointing to springframework/springsource to spring.io.
Remove links that have no redirection
BATCH-2194: Reference documentation for Spring Batch's JSR-352 implementation