Use jldoctest on with_logabsdet_jacobian example

Author: oschulz

src/with_ladj.jl

@@ -14,9 +14,9 @@ For `(y, ladj) = with_logabsdet_jacobian(f, x)`, the following must hold true:
 `with_logabsdet_jacobian` comes with support for broadcasted/mapped functions
 (via `Base.Fix1`) and (Julia >=v1.6 only) `ComposedFunction`.
 
-Example:
+# Examples
 
-```julia
+```jldoctest a
 foo(x) = inv(exp(-x) + 1)
 
 function ChangesOfVariables.with_logabsdet_jacobian(::typeof(foo), x)
@@ -28,14 +28,29 @@ end
 x = 4.2
 y, ladj_y = with_logabsdet_jacobian(foo, x)
 
-X = rand(10)
+# output
+
+(0.9852259683067269, -4.229768509343836)
+```
+
+```jldoctest a
+X = [3, 7, 5]
 broadcasted_foo = Base.Fix1(broadcast, foo)
 Y, ladj_Y = with_logabsdet_jacobian(broadcasted_foo, X)
 
+# output
+
+([0.9525741268224334, 0.9990889488055994, 0.9933071490757153], -15.112428333033268)
+```
+
+```jldoctest a
 # Requires Julia >= v1.6:
 z, ladj_z = with_logabsdet_jacobian(log ∘ foo, x)
-z == log(foo(x))
-ladj_z == ladj_y + with_logabsdet_jacobian(log, y)[2]
+z == log(foo(x)) && ladj_z == ladj_y + with_logabsdet_jacobian(log, y)[2]
+
+# output
+
+true
 ```
 """
 function with_logabsdet_jacobian end