Docstring for one more normpath method. (JuliaLang#33700)

* Docstring for one more normpath method.

* normpath and abspath always return String.

base/path.jl

@@ -319,7 +319,7 @@ julia> joinpath("/home/myuser", "example.jl")
 joinpath
 
 """
- normpath(path::AbstractString) -> AbstractString
+ normpath(path::AbstractString) -> String
 
 Normalize a path, removing "." and ".." entries.
 
@@ -362,18 +362,25 @@ function normpath(path::String)
  end
  string(drive,path)
 end
+
+"""
+ normpath(path::AbstractString, paths::AbstractString...) -> String
+
+Convert a set of paths to a normalized path by joining them together and removing
+"." and ".." entries. Equivalent to `normpath(joinpath(path, paths...))`.
+"""
 normpath(a::AbstractString, b::AbstractString...) = normpath(joinpath(a,b...))
 
 """
- abspath(path::AbstractString) -> AbstractString
+ abspath(path::AbstractString) -> String
 
 Convert a path to an absolute path by adding the current directory if necessary.
 Also normalizes the path as in [`normpath`](@ref).
 """
 abspath(a::String) = normpath(isabspath(a) ? a : joinpath(pwd(),a))
 
 """
- abspath(path::AbstractString, paths::AbstractString...) -> AbstractString
+ abspath(path::AbstractString, paths::AbstractString...) -> String
 
 Convert a set of paths to an absolute path by joining them together and adding the
 current directory if necessary. Equivalent to `abspath(joinpath(path, paths...))`.