Update src/differentials/abstract_zero.jl

Co-authored-by: Lyndon White <oxinabox@ucc.asn.au>

Author: Pietro Vertechi

src/differentials/abstract_zero.jl

@@ -3,8 +3,8 @@
 
 This abstract type encompasses zero-like differential types.
 If an AD system encounters a propagator that takes as input only subtypes of `AbstractZero`,
-then it can stop performing AD operations. All propagators are linear functions, and thus
-the final result will be zero.
+then it can stop performing AD operations.
+All propagators are linear functions, and thus the final result will be zero.
 
 All `AbstractZero` subtypes are singleton types.
 There are two of them: [`Zero()`](@ref) and [`DoesNotExist()`](@ref).