add links and references to pyprog:scipy

Author: mmcky

lectures/intro_supply_demand.md

@@ -797,6 +797,12 @@ pencil and paper.
 
 Maximize it using `scipy.optimize.minimize_scalar` instead.
 
+```{seealso}
+Our [SciPy](https://python-programming.quantecon.org/scipy.html) lecture has
+a section on [Optimization](https://python-programming.quantecon.org/scipy.html#optimization)
+is a useful resource to find out more. 
+```
+
 ```
 
 
@@ -837,6 +843,12 @@ $$
 
 You can use `scipy.optimize.newton` to compute the root.
 
+```{seealso}
+Our [SciPy](https://python-programming.quantecon.org/scipy.html) lecture has
+a section on [Roots and Fixed Points](https://python-programming.quantecon.org/scipy.html#roots-and-fixed-points)
+is a useful resource to find out more. 
+```
+
 Initialize `newton` with a starting guess somewhere close to 1.0.
 
 (Similar initial conditions will give the same result.)