[spec] Adjust binary format of element segments (#46)

Author: gahaas

document/core/binary/modules.rst

@@ -319,7 +319,9 @@ It decodes into a vector of :ref:`element segments <syntax-elem>` that represent
    \production{element section} & \Belemsec &::=&
      \X{seg}^\ast{:}\Bsection_9(\Bvec(\Belem)) &\Rightarrow& \X{seg} \\
    \production{element segment} & \Belem &::=&
-     x{:}\Btableidx~~e{:}\Bexpr~~y^\ast{:}\Bvec(\Bfuncidx)
+     \hex{00}~~e{:}\Bexpr~~y^\ast{:}\Bvec(\Bfuncidx)
+       &\Rightarrow& \{ \ETABLE~0, \EOFFSET~e, \EINIT~y^\ast \} \\ &&|&
+     \hex{02}~~x{:}\Btableidx~~e{:}\Bexpr~~y^\ast{:}\Bvec(\Bfuncidx)
        &\Rightarrow& \{ \ETABLE~x, \EOFFSET~e, \EINIT~y^\ast \} \\
    \end{array}