Add comment for gemv stride adjustment

Written by jturner314 on the PR.

src/linalg/impl_linalg.rs

@@ -586,6 +586,10 @@ pub fn general_mat_vec_mul<A, S1, S2, S3>(alpha: A,
                     if blas_compat_1d::<$ty, _>(&x)
                         && blas_compat_1d::<$ty, _>(&y)
                     {
+                        // Determine stride between rows or columns. Note that the stride is
+                        // adjusted to at most `k` or `m` to handle the case of a matrix with a
+                        // trivial (length 1) dimension, since the stride for the trivial dimension
+                        // may be arbitrary.
                         let a_trans = CblasNoTrans;
                         let a_stride = match layout {
                             CBLAS_LAYOUT::CblasRowMajor => a.strides()[0].max(k as isize) as blas_index,