[spec] Add missing i32x4.extadd_pairwise_i16x8_u instruction to text format

Author: rossberg

document/core/text/instructions.rst

@@ -800,6 +800,7 @@ Vector constant instructions have a mandatory :ref:`shape <syntax-vec-shape>` de
      \text{i32x4.all\_true} &\Rightarrow& \I32X4.\ALLTRUE\\ &&|&
      \text{i32x4.bitmask} &\Rightarrow& \I32X4.\BITMASK\\ &&|&
      \text{i32x4.extadd\_pairwise\_i16x8\_s} &\Rightarrow& \I32X4.\EXTADDPAIRWISE\K{\_i16x8\_s}\\ &&|&
+     \text{i32x4.extadd\_pairwise\_i16x8\_u} &\Rightarrow& \I32X4.\EXTADDPAIRWISE\K{\_i16x8\_u}\\ &&|&
      \text{i32x4.extend\_low\_i16x8\_s} &\Rightarrow& \I32X4.\VEXTEND\K{\_low\_i16x8\_s}\\ &&|&
      \text{i32x4.extend\_high\_i16x8\_s} &\Rightarrow& \I32X4.\VEXTEND\K{\_high\_i16x8\_s}\\ &&|&
      \text{i32x4.extend\_low\_i16x8\_u} &\Rightarrow& \I32X4.\VEXTEND\K{\_low\_i16x8\_u}\\ &&|&