remove reference and add note

Author: MeKaustubh07

lib/node_modules/@stdlib/blas/ext/base/ndarray/scusumors/README.md

@@ -77,6 +77,7 @@ The function has the following parameters:
 ## Notes
 
 -   If provided an empty one-dimensional input ndarray, the function returns the output ndarray unchanged.
+-   Ordinary recursive summation (i.e., a "simple" sum) is performant, but can incur significant numerical error. If performance is paramount and error tolerated, using ordinary recursive summation is acceptable; in all other cases, exercise due caution.
 
 </section>
 
@@ -119,10 +120,6 @@ console.log( ndarray2array( v ) );
 
 <section class="references">
 
-## References
-
--   Shewchuk, Jonathan Richard. 1997. "Adaptive Precision Floating-Point Arithmetic and Fast Robust Geometric Predicates." _Discrete & Computational Geometry_ 18 (3): 305–63. doi:[10.1007/pl00009321][@shewchuk:1997a].
-
 </section>
 
 <!-- /.references -->
@@ -139,8 +136,6 @@ console.log( ndarray2array( v ) );
 
 <section class="links">
 
-[@shewchuk:1997a]: https://doi.org/10.1007/pl00009321
-
 </section>
 
 <!-- /.links -->