Caching refactoring and documentation

[m-stego]

The caching part is not documented yet. This should be done.

Before documenting it we might check if we can improve the caching config/implementation as it's probably outdated.

Something defining Caches in code like

@Bean
fun xyDataCache(): Cache {
        return ClfCacheBuilder()
                .name(CACHENAME)
                .expireAfterAccess(6, TimeUnit.HOURS)
                .build()
}

would be nice.

So that you can use the name easily in the Annotation @Cacheable(CACHENAME)