Refactor Encryption Documentation

[lorriborri]

Situation

SecHub encryption concept is partially in the TechDoc and partially in the Architecture Doc

Wanted

The Encryption concept should be easy to find and located in one Documentation. Further for the variable password_source_data there should exist a note which says that this variable should never contain the password.

Solution

Move/ Include the concept_sechub_data_encryption.adoc and the concept_pds_data_encryption.adoc at the same documentation. Add a Note to the section for the password_source_data variable.