A minor "typo" in the GMP documentation of mpn_mul_1

[Torbjorn Granlund]

Will Galway <galway at math.uiuc.edu> writes:

  Edition 5.0.5 of the GMP manual, in the section on mpn_mul_1, states:
    Don't call this function if S2LIMB is a power of 2; use `mpn_lshift'
  with a count equal to the logarithm
    of S2LIMB instead, for optimal speed.
  
  Of course, it would be more correct to write "base-2 logarithm"
  instead of "logarithm".
  
I think we expect GMP users to be able to deduce that the logarithm must
be 2 here!

-- 
Torbjörn