Add a docstring for Base.divgcd (JuliaLang#53769)

Co-authored-by: Sukera <[email protected]>

Author: putianyi889

base/rational.jl

@@ -49,6 +49,13 @@ Rational(n::T, d::T) where {T<:Integer} = Rational{T}(n, d)
 Rational(n::Integer, d::Integer) = Rational(promote(n, d)...)
 Rational(n::Integer) = unsafe_rational(n, one(n))
 
+"""
+    divgcd(x::Integer, y::Integer)
+
+Returns `(x÷gcd(x,y), y÷gcd(x,y))`.
+
+See also [`div`](@ref), [`gcd`](@ref).
+"""
 function divgcd(x::TX, y::TY)::Tuple{TX, TY} where {TX<:Integer, TY<:Integer}
     g = gcd(uabs(x), uabs(y))
     div(x,g), div(y,g)