Adds docstring

src/generate_tangent.jl

@@ -1,3 +1,8 @@
+"""
+    rand_tangent([rng::AbstractRNG], x)
+
+Returns a randomly generated tangent vector appropriate for the primal value `x`.
+"""
 rand_tangent(x) = rand_tangent(Random.GLOBAL_RNG, x)
 
 function rand_tangent(rng::AbstractRNG, x::Union{Symbol, AbstractChar, AbstractString})
@@ -17,5 +22,3 @@ end
 function rand_tangent(rng::AbstractRNG, xs::T) where {T<:NamedTuple}
     return Composite{T}(; map(x -> rand_tangent(rng, x), xs)...)
 end
-
-rand_tangent(x) = rand_tangent(Random.default_rng(), x)