Fix formatting in RELEASES.md

Author: jturner314

RELEASES.md

@@ -95,10 +95,10 @@ API changes
     time if an unsupported type for *expr* is used instead of panicking at
     runtime.
 
-  https://github.com/rust-ndarray/ndarray/pull/570
-  https://github.com/rust-ndarray/ndarray/pull/940
-  https://github.com/rust-ndarray/ndarray/pull/943
-  https://github.com/rust-ndarray/ndarray/pull/945
+  https://github.com/rust-ndarray/ndarray/pull/570 <br>
+  https://github.com/rust-ndarray/ndarray/pull/940 <br>
+  https://github.com/rust-ndarray/ndarray/pull/943 <br>
+  https://github.com/rust-ndarray/ndarray/pull/945 <br>
 
 - Removed already deprecated methods by [@bluss]: