[Docs] Reformat sparse example (pytorch#154785)

Not sure why, but rst fails to colorize multiline inputs, but works fine for single line commands
Test plan:
| [Before](https://docs.pytorch.org/docs/main/sparse.html#construction)  | [After](https://docs-preview.pytorch.org/pytorch/pytorch/154785/sparse.html#construction) |
| ------------- | ------------- |
| <img width="466" alt="image" src="https://github.com/user-attachments/assets/96a5c52a-1804-4d05-a5cf-c10221aaddf6" />  | <img width="477" alt="image" src="https://github.com/user-attachments/assets/99565288-5c0b-4e8e-bd60-f016ebc207b5" />  |

Fixes pytorch#154779

Pull Request resolved: pytorch#154785
Approved by: https://github.com/janeyx99, https://github.com/Skylion007

Author: malfet

docs/source/sparse.rst

@@ -360,8 +360,7 @@ Suppose we want to define a sparse tensor with the entry 3 at location
 Unspecified elements are assumed to have the same value, fill value,
 which is zero by default. We would then write:
 
-    >>> i = [[0, 1, 1],
-             [2, 0, 2]]
+    >>> i = [[0, 1, 1], [2, 0, 2]]
     >>> v =  [3, 4, 5]
     >>> s = torch.sparse_coo_tensor(i, v, (2, 3))
     >>> s