Fix sphinx/build_docs warnings for data_structures/binary_tree/mirror_binary_tree (#12470)

data_structures/binary_tree/mirror_binary_tree.py

@@ -56,6 +56,8 @@ class Node:
 def make_tree_seven() -> Node:
     r"""
     Return a binary tree with 7 nodes that looks like this:
+    ::
+
            1
          /   \
         2     3
@@ -81,6 +83,8 @@ def make_tree_seven() -> Node:
 def make_tree_nine() -> Node:
     r"""
     Return a binary tree with 9 nodes that looks like this:
+    ::
+
             1
            / \
           2   3
@@ -117,7 +121,8 @@ def main() -> None:
     >>> tuple(tree.mirror())
     (6, 3, 1, 9, 5, 2, 8, 4, 7)
 
-    nine_tree:
+    nine_tree::
+
             1
            / \
           2   3
@@ -126,7 +131,8 @@ def main() -> None:
        / \   \
       7   8   9
 
-    The mirrored tree looks like this:
+    The mirrored tree looks like this::
+
           1
          / \
         3   2