Undocumented syntax for wasm-decompile

[phoebehfharris]

In the syntax for the C-like language produced by obj-decompile, the following syntax's behaviour is not documented anywhere in the WABT docs:

identifier[x@y]

I believe x is an offset and y is the number of bytes being indexed for a load instruction, but again, since there's no documentation, I do not fully understand the syntax enough to add to the documentation confidently myself