Finalize 5.3-RC1 release notes

Author: marcphilipp

documentation/src/docs/asciidoc/release-notes/release-notes-5.3.0-RC1.adoc

@@ -1,9 +1,10 @@
 [[release-notes-5.3.0-RC1]]
 == 5.3.0-RC1
 
-*Date of Release:* ❓
+*Date of Release:* August 13, 2018
 
-*Scope:* ❓
+*Scope:* Finishing touches on parallel test execution and output capturing, bug fixes and
+miscellaneous usability improvements.
 
 For a complete list of all _closed_ issues and pull requests for this release, consult the
 link:{junit5-repo}+/milestone/27?closed=1+[5.3 RC1] milestone page in the JUnit repository