Release process: make text snippet directly copy'n'pastable

wiki/src/contribute/release_process.mdwn

@@ -345,12 +345,19 @@ Then, launch an editor for the needed cleanup of the result:
 
 Changelog entries can be dispatched into those usual sections:
 
- * Major changes
- * Security fixes
- * Bugfixes
- * Minor improvements and updates
- * Build system
- * Test suite
+<pre>
+  * Major changes
+
+  * Security fixes
+
+  * Bugfixes
+
+  * Minor improvements and updates
+
+  * Build system
+
+  * Test suite
+</pre>
 
 Then, gather other useful information from: