fix: add stub definition to webassebmly numeric DD

Author: nschonni

files/en-us/webassembly/reference/numeric/index.md

@@ -89,12 +89,19 @@ WebAssembly numeric instructions.
 ## Bitwise
 
 - [`AND`](/en-US/docs/WebAssembly/Reference/Numeric/AND)
+  - : Used for performing a bitwise AND.
 - [`OR`](/en-US/docs/WebAssembly/Reference/Numeric/OR)
+  - : Used for performing a bitwise OR.
 - [`XOR`](/en-US/docs/WebAssembly/Reference/Numeric/XOR)
+  - : Used for performing a bitwise XOR.
 - [`Left shift`](/en-US/docs/WebAssembly/Reference/Numeric/Left_shift)
+  - : Used for performing a bitwise left-shift.
 - [`Right shift`](/en-US/docs/WebAssembly/Reference/Numeric/Right_shift)
+  - : Used for performing a bitwise left-shift.
 - [`Left rotate`](/en-US/docs/WebAssembly/Reference/Numeric/Left_rotate)
+  - : Used for performing a bitwise left-rotate.
 - [`Right rotate`](/en-US/docs/WebAssembly/Reference/Numeric/Right_rotate)
+  - : Used for performing a bitwise right-rotate.
 - [`Count leading zeros`](/en-US/docs/WebAssembly/Reference/Numeric/Count_leading_zeros)
   - : Count the amount of leading zeros in a numbers binary representation.
 - [`Count trailing zeros`](/en-US/docs/WebAssembly/Reference/Numeric/Count_trailing_zeros)