fix: add rust in default language list (LeetCode-OpenSource#412)

SF-Zhou · jdneo · commit a3528505543b · 2019-09-10T18:59:33.000+08:00
diff --git a/package.json b/package.json
@@ -305,6 +305,7 @@
                             "python",
                             "python3",
                             "ruby",
+                            "rust",
                             "scala",
                             "swift"
                         ],
