Add compat note for printstyled (#42547)

(cherry picked from commit f2080d5)

Author: mcabbott

base/strings/io.jl

@@ -15,7 +15,7 @@ avoid Julia-specific details.
 For example, `show` displays strings with quotes, and `print` displays strings
 without quotes.
 
-[`string`](@ref) returns the output of `print` as a string.
+See also [`println`](@ref), [`string`](@ref), [`printstyled`](@ref).
 
 # Examples
 ```jldoctest
@@ -57,6 +57,8 @@ end
 Print (using [`print`](@ref)) `xs` followed by a newline.
 If `io` is not supplied, prints to [`stdout`](@ref).
 
+See also [`printstyled`](@ref) to add colors etc.
+
 # Examples
 ```jldoctest
 julia> println("Hello, world")

base/util.jl

@@ -113,14 +113,18 @@ end
 
 Print `xs` in a color specified as a symbol or integer, optionally in bold.
 
-`color` may take any of the values $(Base.available_text_colors_docstring)
+Keyword `color` may take any of the values $(Base.available_text_colors_docstring)
 or an integer between 0 and 255 inclusive. Note that not all terminals support 256 colors.
-If the keyword `bold` is given as `true`, the result will be printed in bold.
-If the keyword `underline` is given as `true`, the result will be printed underlined.
-If the keyword `blink` is given as `true`, the result will blink.
-If the keyword `reverse` is given as `true`, the result will have foreground and background colors inversed.
-If the keyword `hidden` is given as `true`, the result will be hidden.
-Keywords can be given in any combination.
+
+Keywords `bold=true`, `underline=true`, `blink=true` are self-explanatory.
+Keyword `reverse=true` prints with foreground and background colors exchanged,
+and `hidden=true` should be invisibe in the terminal but can still be copied.
+These properties can be used in any combination.
+
+See also [`print`](@ref), [`println`](@ref), [`show`](@ref).
+
+!!! compat "Julia 1.7"
+    Keywords except `color` and `bold` were added in Julia 1.7.
 """
 printstyled(io::IO, msg...; bold::Bool=false, underline::Bool=false, blink::Bool=false, reverse::Bool=false, hidden::Bool=false, color::Union{Int,Symbol}=:normal) =
     with_output_color(print, color, io, msg...; bold=bold, underline=underline, blink=blink, reverse=reverse, hidden=hidden)