release-notes.txt: add notes for 2019.07 release
release-notes.txt: add notes for 2019.07 release

Co-authored-by: Martine Lenders <2c907b4895f2cbc5b6ae26e9e5a106869e61ece9@fu-berlin.de>
Co-authored-by: Gaëtan Harter <25db78be7c666d99eacb81d0f35148479f604823@fu-berlin.de>
Co-authored-by: Lanzieri Rodriguez <502f649743713a566a320ad97a6cd78f6bef9274@haw-hamburg.de>

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