Scaled offsets for compressed encodings

[tovine]

Hi,

First of all, I just noticed that you had taken over and started the proper fast-track process for this extension - thanks a lot!
I found one thing in the description for the compressed instructions:

In the case of the stack-pointer relative instructions we have

It computes its effective address by adding the zero-extended offset, scaled by 8

But not for the others.
Shouldn't it be the same there as well? I see the existing RV64 compressed encodings have the same scaling factor (by including immediate bits [7:3], and it would be beneficial to keep that here as well, for the increased immediate range (and avoiding the possibility for misaligned accesses, unless that's actually a desired feature).

Even if this was already the intended behavior, we should state it explicitly so there's no room for ambiguity