[releng] Correct baseline mention in update site description
[releng] Correct baseline mention in update site description

According to [1], our baseline is Luna.

Note that since commit c60b104 we have no target platforms for
anything older than Eclipse Mars.

[1] https://wiki.eclipse.org/EGit/FAQ#What_versions_of_Eclipse_does_EGit_target.3F

Change-Id: I8e17540da3f72563baefebab39cc2054a270e5fb
Signed-off-by: Thomas Wolf <8459781ac8835441ed2b344527c00d1cc5d7fce6@paranor.ch>

collaborative-modeling/egit,collaborative-modeling/egit