Description NG decoration (#635)

Author: mi-ayala

docs/src/manual/construction.md

@@ -133,10 +133,19 @@ These are all examples of ill-formed intervals, resulting in the decoration `ill
 
 ### Guarantee
 
-A *guarantee* is yet another label, independent of decorations, and not described by the IEEE Standard 1788-2015 specifications. Its purpose is to accomodate for Julia's extensive conversion and promotion system, while retaining reliability in computations. Specifically, an interval `x` constructed via [`interval`](@ref) satisfies `isguaranteed(x) == true`. However, if a call to `convert(::Type{<:Interval}, ::Real)` occurs, then the resulting interval `x` satisfies `isguaranteed(x) == false`.
+A *guarantee* is yet another label, independent of decorations, and not described by the IEEE Standard 1788-2015 specifications. Its purpose is to accomodate for Julia's extensive conversion and promotion system, while retaining reliability in computations. Specifically, an interval `x` constructed via [`interval`](@ref) satisfies `isguaranteed(x) == true`. However, if a call to `convert(::Type{<:Interval}, ::Real)` occurs, then the resulting interval `x` satisfies `isguaranteed(x) == false`, receiving the 'NG' (not guaranteed) label. For instance, consider the following examples:
+
+```@repl construction
+ convert(Interval{Float64}, 1.) # considered "not guaranteed" as this call can be done implicitly
+```
+
+```@repl construction
+interval(1) # considered "guaranteed" as the user explicitly constructed the interval
+```
 
 In contrast, a [`BareInterval`](@ref) can only be constructed via [`bareinterval`](@ref), it is not a subtype of `Real`, and there are no allowed conversion with `Number`. Thus, this interval type is always guaranteed.
 
+
 !!! danger
     A user interested in validated numerics should **always** have a resulting interval for which [`isguaranteed`](@ref) is `true`.