Update dgl.sparse rst. (#5201)

* dgl

* blabla
Co-authored-by: Steve <ubuntu@ip-172-31-34-29.ap-northeast-1.compute.internal>

docs/source/api/python/dgl.sparse_v0.rst

 .. _apibackend:
 
-dgl.sparse
+🆕 dgl.sparse
 =================================
 
 `dgl.sparse` is a library for sparse operators that are commonly used in GNN models.
@@ -60,16 +60,17 @@ Sparse matrix class
                                     [5, 5]]),
                      shape=(3, 3), nnz=5)
 
-Creators
+Creation Ops
 ````````
 
 .. autosummary::
     :toctree: ../../generated/
 
+    spmatrix
+    val_like
     from_coo
     from_csr
     from_csc
-    val_like
 
 Attributes and methods
 ``````````````````````