[MRG + 1] docs: Change example of KDTree to prevent DeprecationWarning (scikit-learn#6962)

* docs: Change example of KDTree to prevent DeprecationWarning

- fill in missing import statement of sklearn.neighbors.KDTree
- wrap X in a list

Changes to be committed:
	modified:   sklearn/neighbors/binary_tree.pxi

Resolves: scikit-learn#6906

* docs: remove import statement of KDTree in example of KDTree

- remove import statement of sklearn.neighbors.KDTree

Changes to be committed:
	modified:   sklearn/neighbors/binary_tree.pxi

Resolves: scikit-learn#6906

Author: jannab

sklearn/neighbors/binary_tree.pxi

@@ -293,11 +293,10 @@ Examples
 Query for k-nearest neighbors
 
     >>> import numpy as np
-
     >>> np.random.seed(0)
     >>> X = np.random.random((10, 3))  # 10 points in 3 dimensions
     >>> tree = {BinaryTree}(X, leaf_size=2)              # doctest: +SKIP
-    >>> dist, ind = tree.query(X[0], k=3)                # doctest: +SKIP
+    >>> dist, ind = tree.query([X[0]], k=3)                # doctest: +SKIP
     >>> print ind  # indices of 3 closest neighbors
     [0 3 1]
     >>> print dist  # distances to 3 closest neighbors