correct DOS line endings

doc/contributions.txt

@@ -65,15 +65,15 @@ Aimee Trescothick
 Alejandro Rosenthal
 	VWR-1184
 Aleric Inglewood
-	SNOW-84
+	SNOW-84
 	SNOW-240
-	SNOW-477
+	SNOW-477
 	SNOW-522
 	SNOW-626
-	SNOW-744
+	SNOW-744
 	SNOW-756
 	SNOW-764
-	SNOW-766
+	SNOW-766
 	SNOW-800
 	VWR-10001
 	VWR-10579
@@ -100,7 +100,7 @@ Aleric Inglewood
 	VWR-24519
 	VWR-24520
 	STORM-163
-	STORM-864
+	STORM-864
 	STORM-955
 	STORM-960
 Ales Beaumont