add Stetmann commander (#93)

* add Stetmann commander

* move to alphabetical

Author: StoicLoofah

sc2reader/data/attributes.json

@@ -710,6 +710,7 @@
         "Kerr": "Kerrigan",
         "Nova": "Nova",
         "Rayn": "Raynor",
+        "Stet": "Stetmann",
         "Stuk": "Stukov",
         "Swan": "Swann",
         "Tych": "Tychus",