fix docstring for alignment (#28409)

base/arrayshow.jl

@@ -47,7 +47,7 @@ end
 const undef_ref_alignment = (3,3)
 
 """
-`alignment(X, rows, cols, cols_if_complete, cols_otherwise, sep)` returns the
+`alignment(io, X, rows, cols, cols_if_complete, cols_otherwise, sep)` returns the
 alignment for specified parts of array `X`, returning the (left,right) info.
 It will look in X's `rows`, `cols` (both lists of indices)
 and figure out what's needed to be fully aligned, for example looking all

base/show.jl

@@ -2052,20 +2052,20 @@ end
 
 
 """
-`alignment(X)` returns a tuple (left,right) showing how many characters are
+`alignment(io, X)` returns a tuple (left,right) showing how many characters are
 needed on either side of an alignment feature such as a decimal point.
 """
 alignment(io::IO, x::Any) = (0, length(sprint(show, x, context=io, sizehint=0)))
 alignment(io::IO, x::Number) = (length(sprint(show, x, context=io, sizehint=0)), 0)
-"`alignment(42)` yields (2,0)"
+"`alignment(stdout, 42)` yields (2, 0)"
 alignment(io::IO, x::Integer) = (length(sprint(show, x, context=io, sizehint=0)), 0)
-"`alignment(4.23)` yields (1,3) for `4` and `.23`"
+"`alignment(stdout, 4.23)` yields (1, 3) for `4` and `.23`"
 function alignment(io::IO, x::Real)
     m = match(r"^(.*?)((?:[\.eEfF].*)?)$", sprint(show, x, context=io, sizehint=0))
     m === nothing ? (length(sprint(show, x, context=io, sizehint=0)), 0) :
                    (length(m.captures[1]), length(m.captures[2]))
 end
-"`alignment(1 + 10im)` yields (3,5) for `1 +` and `_10im` (plus sign on left, space on right)"
+"`alignment(stdout, 1 + 10im)` yields (3, 5) for `1 +` and `_10im` (plus sign on left, space on right)"
 function alignment(io::IO, x::Complex)
     m = match(r"^(.*[^ef][\+\-])(.*)$", sprint(show, x, context=io, sizehint=0))
     m === nothing ? (length(sprint(show, x, context=io, sizehint=0)), 0) :