fix spec

Author: ckrause

spec.markdown

@@ -286,7 +286,6 @@ gcd $0,5   ; $0 := 1
 ## **lex** (Largest Exponent)
 
 Largest exponent of the source dividing the target.
-Greatest common divisor of target and source.
 
 An operation `lex a,b` computes the largest exponent of `b` that divides `a`, and assigns it to `a`. The result is always a non-negtive number. If `a` is zero or `b` is zero or `b` is one, the result is always zero.