repr: update docstring for possible values of the context argument

base/strings/io.jl

@@ -199,8 +199,9 @@ print(io::IO, s::Union{String,SubString{String}}) = (write(io, s); nothing)
 Create a string from any value using the [`show`](@ref) function.
 You should not add methods to `repr`; define a `show` method instead.
 
-The optional keyword argument `context` can be set to an `IO` or [`IOContext`](@ref)
-object whose attributes are used for the I/O stream passed to `show`.
+The optional keyword argument `context` can be set to a `:key=>value` pair, a
+tuple of `:key=>value` pairs, or an `IO` or [`IOContext`](@ref) object whose
+attributes are used for the I/O stream passed to `show`.
 
 Note that `repr(x)` is usually similar to how the value of `x` would
 be entered in Julia.  See also [`repr(MIME("text/plain"), x)`](@ref) to instead