add get_direct_addressing_ModRM and test_*, fix a couple bugs/typos, add 'reg value' as register metadata

twasm/README.md

@@ -127,13 +127,15 @@ type metadata for the different types is as follows:
 ```
 
 ```
-+------------------+
-| type 0x2         |
-+----------+-------+
-| 31    26 | 25 24 |
-+----------+-------+
-| reserved | width |
-+----------+-------+
++------------------------------+
+| type 0x2                     |
++----------+-----------+-------+
+| 31    29 | 28     26 | 25 24 |
++----------+-----------+-------+
+| reserved | reg value | width |
++----------+-----------+-------+
+
+; reg is the value that cooresponds to the register in the ModR/M byte
 
 ; width:
 00b ; 8 bit