feat: add the section of Graph Traversal (#367)

* Graph dev

* Add the section of Graph Traversal.

* Add missing Vertex.java

* Add mkdocs.yml

* Update numbering

* Fix indentation and update array.md

codes/java/chapter_graph/graph_adjacency_matrix.java

@@ -100,7 +100,7 @@ public class graph_adjacency_matrix {
         /* 初始化无向图 */
         // 请注意，edges 元素代表顶点索引，即对应 vertices 元素索引
         int[] vertices = { 1, 3, 2, 5, 4 };
-        int[][] edges = { { 0, 1 }, { 1, 2 }, { 2, 3 }, { 0, 3 }, { 2, 4 }, { 3, 4 } };
+        int[][] edges = { { 0, 1 }, { 0, 3 }, { 1, 2 }, { 2, 3 }, { 2, 4 }, { 3, 4 } };
         GraphAdjMat graph = new GraphAdjMat(vertices, edges);
         System.out.println("\n初始化后，图为");
         graph.print();