Copying files to root dir using gradle Copy task is bad practice

[skuzzle]

During release, we copy updated readme and docs to the project's root dir so that they are in the proper location to be displayed by GitHub and GitHub pages.
However, copying files to the root dir makrs to whole root dir as task output which effectivle subverts the whole build caching done by gradle.

See also: https://stackoverflow.com/a/47884138/2489557