fix the word warning by Xcode.

MJRefresh/Custom/Footer/Auto/MJRefreshAutoNormalFooter.m

@@ -31,7 +31,7 @@ - (void)setActivityIndicatorViewStyle:(UIActivityIndicatorViewStyle)activityIndi
     self.loadingView = nil;
     [self setNeedsLayout];
 }
-#pragma makr - 重写父类的方法
+#pragma mark - 重写父类的方法
 - (void)prepare
 {
     [super prepare];

MJRefresh/Custom/Footer/Back/MJRefreshBackNormalFooter.m

@@ -45,7 +45,7 @@ - (void)setActivityIndicatorViewStyle:(UIActivityIndicatorViewStyle)activityIndi
     self.loadingView = nil;
     [self setNeedsLayout];
 }
-#pragma makr - 重写父类的方法
+#pragma mark - 重写父类的方法
 - (void)prepare
 {
     [super prepare];