fix incorrect comment

Author: Kasra-G

packages/aws-cdk-lib/aws-stepfunctions/lib/state-graph.ts

@@ -215,7 +215,7 @@ export class StateGraph {
     const discoveredStateGraphs = new Set<StateGraph>();
     const stateGraphsToSearch: StateGraph[] = [this];
 
-    // Do a BFS of all sub graphs
+    // Do a DFS of all sub graphs
     while (stateGraphsToSearch.length > 0) {
       const stateGraph = stateGraphsToSearch.pop()!;