Merge milestone and RC release notes for 5.3 GA

Issue: #1541

Author: sbrannen

documentation/src/docs/asciidoc/release-notes/index.adoc

@@ -9,17 +9,12 @@ Stefan Bechtold; Sam Brannen; Johannes Link; Matthias Merdes; Marc Philipp; Chri
 
 This document contains the _change log_ for all JUnit 5 releases since 5.2 GA.
 
-Please refer to the <<../user-guide/index.adoc#user-guide,User Guide>> for
-comprehensive reference documentation for programmers writing tests,
-extension authors, and engine authors as well as build tool and IDE
-vendors.
+Please refer to the <<../user-guide/index.adoc#user-guide,User Guide>> for comprehensive
+reference documentation for programmers writing tests, extension authors, and engine
+authors as well as build tool and IDE vendors.
 
 include::../link-attributes.adoc[]
 
 include::release-notes-5.3.0.adoc[]
 
-include::release-notes-5.3.0-RC1.adoc[]
-
-include::release-notes-5.3.0-M1.adoc[]
-
 include::release-notes-5.2.0.adoc[]