Add 5.2 RC1 release notes

Author: marcphilipp

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

@@ -16,6 +16,8 @@ vendors.
 
 include::../link-attributes.adoc[]
 
+include::release-notes-5.2.0-RC1.adoc[]
+
 include::release-notes-5.2.0-M1.adoc[]
 
 include::release-notes-5.1.1.adoc[]

documentation/src/docs/asciidoc/release-notes/release-notes-5.2.0-RC1.adoc

@@ -0,0 +1,26 @@
+[[release-notes-5.2.0-RC1]]
+== 5.2.0-RC1
+
+*Date of Release:* April 22, 2018
+
+*Scope:* Improvements to User Guide and Javadoc
+
+For a complete list of all _closed_ issues and pull requests for this release, consult the
+link:{junit5-repo}+/milestone/25?closed=1+[5.2 RC1] milestone page in the JUnit repository
+on GitHub.
+
+
+[[release-notes-5.2.0-RC1-junit-platform]]
+=== JUnit Platform
+
+No changes.
+
+[[release-notes-5.2.0-RC1-junit-jupiter]]
+=== JUnit Jupiter
+
+No changes.
+
+[[release-notes-5.2.0-RC1-junit-vintage]]
+=== JUnit Vintage
+
+No changes.