invalid assembly instructions in project 6 files

[jackc12]

nand2tetris/web-ide#669
nand2tetris/web-ide#670

diff --git a/projects/06/pong/PongL.asm b/projects/06/pong/PongL.asm
index 17c1044..e7e4e58 100644
--- a/projects/06/pong/PongL.asm
+++ b/projects/06/pong/PongL.asm
@@ -132,7 +132,7 @@ D=M-D
 @2
 M=D
 @0
-MD=M+1
+DM=M+1
 @1
 M=D
 @14
diff --git a/projects/06/rect/RectL.asm b/projects/06/rect/RectL.asm
index e97c09b..f2f9646 100644
--- a/projects/06/rect/RectL.asm
+++ b/projects/06/rect/RectL.asm
@@ -25,7 +25,7 @@ D=D+A
 @17
 M=D
 @16
-MD=M-1
+DM=M-1
 @10
 D;JGT
 @23