[SLING-7167] Adjust READMEs

[Oliver Lietz]

hi all,

do we want to use the artifactId or the name for the title in all READMEs, 
e.g. Apache Sling Auth Core vs Apache Sling Authentication Service (we have 
both uncommon ids and names)?

https://issues.apache.org/jira/browse/SLING-7167

Thanks,
O.