Update special block format

Author: Morganov

book/03-git-branching/sections/branch-management.asc

@@ -177,6 +177,7 @@ Now you have a few more tasks in front of you to complete the transition:
 * Close or merge any pull requests that target the old branch.
 
 After you've done all these tasks, and are certain the main branch performs just as the _master_ branch, you can delete the _master_ branch:
+
 [source, console]
 ----
 $ git push origin --delete master