Specify how to obtain all inverses (#1835)

src/Matrix.jl

@@ -3567,11 +3567,15 @@ end
 @doc raw"""
     is_invertible_with_inverse(A::MatrixElem{T}; side::Symbol = :left) where {T <: RingElement}
 
-Given an $n\times m$ matrix $A$ over a ring, return a tuple `(flag, B)`.
-If `side` is `:right` and `flag` is true, $B$ is the right inverse of $A$
-i.e. $AB$ is the $n\times n$ unit matrix. If `side` is `:left` and `flag` is
-true, $B$ is the left inverse of $A$ i.e. $BA$ is the $m\times m$ unit matrix.
-If `flag` is false, no right or left inverse exists.
+Given an $n \times m$ matrix $A$ over a ring, return a tuple `(flag, B)`. If
+`side` is `:right` and `flag` is `true`, $B$ is a right inverse of $A$ i.e.
+$A B$ is the $n \times n$ unit matrix. If `side` is `:left` and `flag` is
+`true`, $B$ is a left inverse of $A$ i.e. $B A$ is the $m \times m$ unit matrix.
+If `flag` is `false`, no right or left inverse exists.
+
+To get the space of all inverses, note that if $B$ and $C$ are both right
+inverses, then $A (B - C) = 0$, and similar for left inverses. Hence from one
+inverse one can find all by making suitable use of [`kernel`](@ref).
 """
 function is_invertible_with_inverse(A::MatrixElem{T}; side::Symbol = :left) where {T <: RingElement}
    if (side == :left && nrows(A) < ncols(A)) || (side == :right && ncols(A) < nrows(A))