remove duplicate doc for optional IOContext arguments (#57847)

Author: jw3126

base/strings/io.jl

@@ -84,10 +84,6 @@ setfield!(typeof(println).name.mt, :max_args, 10, :monotonic)
 
 Call the given function with an I/O stream and the supplied extra arguments.
 Everything written to this I/O stream is returned as a string.
-`context` can be an [`IOContext`](@ref) whose properties will be used, a `Pair`
-specifying a property and its value, or a tuple of `Pair` specifying multiple
-properties and their values. `sizehint` suggests the capacity of the buffer (in
-bytes).
 
 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