[GSS] Update Spring Boot / PAM documentation with regards to narayana

Starting with the Spring Boot 2.1.0 release the Narayana starter has been moved to the SnowDrop project from the spring-projects/spring-boot repository.

For this reason, some properties such as spring.jta.narayana.default-timeout have been dropped and replaced by the properties defined in the SnowDrop project (https://github.com/snowdrop/narayana-spring-boot/blob/main/narayana-spring-boot-core/src/main/java/me/snowdrop/boot/narayana/core/properties/NarayanaProperties.java). For example, narayana.defaultTimeout.

See as a reference, case 02956664