invokelatest docs should say not exported before 1.9 (#50341)

(cherry picked from commit cb6d0f2)

base/essentials.jl

@@ -809,6 +809,9 @@ e.g. long-running event loops or callback functions that may
 call obsolete versions of a function `f`.
 (The drawback is that `invokelatest` is somewhat slower than calling
 `f` directly, and the type of the result cannot be inferred by the compiler.)
+
+!!! compat "Julia 1.9"
+    Prior to Julia 1.9, this function was not exported, and was called as `Base.invokelatest`.
 """
 function invokelatest(@nospecialize(f), @nospecialize args...; kwargs...)
     kwargs = merge(NamedTuple(), kwargs)

base/reflection.jl

@@ -1913,12 +1913,15 @@ end
 """
     @invokelatest f(args...; kwargs...)
 
-Provides a convenient way to call [`Base.invokelatest`](@ref).
+Provides a convenient way to call [`invokelatest`](@ref).
 `@invokelatest f(args...; kwargs...)` will simply be expanded into
 `Base.invokelatest(f, args...; kwargs...)`.
 
 !!! compat "Julia 1.7"
     This macro requires Julia 1.7 or later.
+
+!!! compat "Julia 1.9"
+    Prior to Julia 1.9, this macro was not exported, and was called as `Base.@invokelatest`.
 """
 macro invokelatest(ex)
     f, args, kwargs = destructure_callex(ex)