Add explanation for n_jobs docs
Based on the current implementation, the variable n_jobs is used in 2 places: the NearestNeighbors constructor and kneighbors_graph function.
@@ -374,7 +374,9 @@ class SpectralClustering(ClusterMixin, BaseEstimator):
callable object. Ignored by other kernels.
n_jobs : int, default=None
- The number of parallel jobs to run.
+ The number of parallel jobs to run when `affinity='nearest_neighbors'`
+ or `affinity='precomputed_nearest_neighbors'`. The neighbors search
+ will be done in parallel.
``None`` means 1 unless in a :obj:`joblib.parallel_backend` context.
``-1`` means using all processors. See :term:`Glossary <n_jobs>`
for more details.
