Notes for cp2k - reproducible builds result

Version annotated: 2.6.1-2
Comments: Embeds the build date and hostname.
Part of patch is
docs partly use this value, but also party use "current-dateTime()" from
some XLST library.

Our notes about issues affecting packages are stored in notes.git and are targeted at packages in Debian in 'unstable/amd64' (unless they say otherwise).