fix test in eip-5656

the test accidentally demonstrated the behavior of MCOPY with length=9,
instead of length=8.

moved the space to byte ethereum#8 for clarity

EIPS/eip-5656.md

@@ -140,32 +140,32 @@ gas used: 6
 
 `MCOPY 0 1 8` - copy 8 bytes from offset 1 to offset 0 (overlapping).
 
-pre:
+pre (space at byte 8):
 
 ```
-000102030405060708 0000000000000000000000000000000000000000000000
+0001020304050607 080000000000000000000000000000000000000000000000
 ```
 
 post:
 
 ```
-010203040506070808 0000000000000000000000000000000000000000000000
+0102030405060708 080000000000000000000000000000000000000000000000
 ```
 
 gas used: 6
 
 `MCOPY 1 0 8` - copy 8 bytes from offset 0 to offset 1 (overlapping).
 
-pre:
+pre (space at byte 8):
 
 ```
-000102030405060708 0000000000000000000000000000000000000000000000
+0001020304050607 080000000000000000000000000000000000000000000000
 ```
 
 post:
 
 ```
-00000102030405060708 00000000000000000000000000000000000000000000
+0000010203040506 080000000000000000000000000000000000000000000000
 ```
 
 gas used: 6