message: Document compact limbs mode of multi-range-check gadget
diff: -//~ The range check gadget is comprised of three circuit gates (`RangeCheck0`, `RangeCheck1`
  -//~ and `Zero`) and can perform range checks on three values of up to 88 bits: $v_0, v_1$ and $v_2$.
  +//~ The multi range check gadget is comprised of three circuit gates (`RangeCheck0`,
  +//~ `RangeCheck1` and `Zero`) and can perform range checks on three values ($v_0,
  +//~ v_1$ and $v_2$) of up to 88 bits each.
  //~
  -//~ Optionally, `RangeCheck0` can be used on its own to perform 64-bit range checks by
  +//~ Values can be copied as inputs to the multi range check gadget in two ways.
  +//~ * [Standard mode] With 3 copies, by copying $v_0, v_1$ and $v_2$ to the first
  +//~ cells of the first 3 rows of the gadget. In this mode the first gate
  +//~ coefficient is set to `0`.
  +//~ * [Compact mode] With 2 copies, by copying $v_2$ to the first cell of the first
  +//~ row and copying $v_{10} = v_0 + 2^{\ell} \cdot v_1$ to the 2nd cell of row 2.
  +//~ In this mode the first gate coefficient is set to `1`.
  +//~
  +//~ The `RangeCheck0` gate can also be used on its own to perform 64-bit range checks by
  //~ constraining witness cells 1-2 to zero.
  //~
  //~ **Byte-order:**
  