D29018: Align description in metainfo.yaml with the one of README.md

[Aleix Pol Gonzalez]

apol accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R174 KContacts

BRANCH
  fixmetainfodescription

REVISION DETAIL
  https://phabricator.kde.org/D29018

To: kossebau, mlaurent, apol
Cc: kde-frameworks-devel, LeGast00n, cblack, michaelh, ngraham, bruns