In 9.4.x and 7.3.x the doc source for the Spring Boot Starter is different for upstream and downstream.

• Modularize the Spring Boot Starter doc source upstream.
• Include the Spring Boot Starter docs on the community site (infinispan.org/documentation).
• Remove the Spring Boot Starter productization docs from infinispan/documentation/src/main/asciidoc.

This task removes duplication of content with downstream source. Also brings the user experience for Spring Boot Starter docs into alignment with the strategy for ISPN 10.