v2019.4: Release notes

Rendered here: https://em.pages.apertis.org/apertis-website/

Links are broken, so here are the pages involved:

• https://em.pages.apertis.org/apertis-website/release/v2019.4/releasenotes/
• https://em.pages.apertis.org/apertis-website/release/v2019.5/release_schedule/
• https://em.pages.apertis.org/apertis-website/policies/releases/

content/release/v2019.4/releasenotes.md

@@ -105,7 +105,8 @@ Image build tools can be found in the Apertis tools repositories.
 ### Infrastructure overview
 
 The [Image build infrastructure
-document]( {{< ref "image-build-infrastructure.md" >}} )
+The
+[Image build infrastructure document]( {{< ref "image-build-infrastructure.md" >}} )
 provides an overview of the image building process and the involved
 services.