prepare release v0.5.2

Author: lkstrp

doc/release_notes.rst

@@ -1,12 +1,17 @@
 Release Notes
 =============
 
-Upcoming Version
-----------------
+.. Upcoming Version
+.. ----------------
+
+Version 0.5.2
+--------------
 
 **Bug Fixes**
 
-* Fix the multiplication with of zero dimensional numpy arrays with linopy objects. This is mainly affecting operations where single numerical items from  pandas objects are selected and used for multiplication.
+* Fix the multiplication with of zero dimensional numpy arrays with linopy objects.
+This is mainly affecting operations where single numerical items from  pandas objects
+are selected and used for multiplication.
 
 Version 0.5.1
 --------------