Update docs

Author: YingboMa

docs/src/tutorials/tearing_parallelism.md

@@ -165,9 +165,9 @@ investigate what this means:
 ```@example tearing
 using ModelingToolkit.BipartiteGraphs
 ts = TearingState(expand_connections(big_rc))
-inc_org = BipartiteGraphs.incidence_matrix(ts.graph)
-blt_org = StructuralTransformations.sorted_incidence_matrix(big_rc, only_algeqs=true, only_algvars=true)
-blt_reduced = StructuralTransformations.sorted_incidence_matrix(sys, only_algeqs=true, only_algvars=true)
+inc_org = BipartiteGraphs.incidence_matrix(ts.structure.graph)
+blt_org = StructuralTransformations.sorted_incidence_matrix(ts, only_algeqs=true, only_algvars=true)
+blt_reduced = StructuralTransformations.sorted_incidence_matrix(ModelingToolkit.get_tearing_state(sys), only_algeqs=true, only_algvars=true)
 ```
 
 ![](https://user-images.githubusercontent.com/1814174/110589027-d4ec9b00-8143-11eb-8880-651da986504d.PNG)