[Koha] Koha 18.05.11 release

The Koha community is proud to announce the release of Koha 18.05.11 This is a maintenance release. The full release notes are available at: https://koha-community.org/koha-18-05-11-release/ Koha 18.05.11 can be downloaded from: http://download.koha-community.org/koha-18.05.11.tar.gz Thanks to everyone who contributed to this release! JesseM & Lucas