Adapted Wording in Service Portfolio Milestones, deleted milestone with process manual in 12.2021 that seems to be doubled with the milestone in 11.2021

"The following destination is shared by multiple files". This is due to
conflicting file names. This is why all the files in the _roadmap folder
got individual names.

In case multiple elements with several dates in one month are inserted,
an additional month layer got added to the roadmap. This changes
ensures, that the month is only displayed once.

to avoid interruping lines