doc: add parens to example |> docstring (#36155)

Author: jonniedie

base/operators.jl

@@ -901,10 +901,11 @@ widen(x::Type{T}) where {T} = throw(MethodError(widen, (T,)))
     |>(x, f)
 
 Applies a function to the preceding argument. This allows for easy function chaining.
+When used with anonymous functions, parentheses are typically required around the definition to get the intended chain.
 
 # Examples
 ```jldoctest
-julia> [1:5;] |> (x->x.^2) |> sum |> inv
+julia> [1:5;] .|> (x -> x^2) |> sum |> inv
 0.01818181818181818
 ```
 """