Fix dead Stanford link in NACA airfoil docs

Author: sbryngelson

docs/documentation/case.md

@@ -349,7 +349,7 @@ Definitions for currently implemented immersed boundary patch types are listed i
 
 - `c`, `t`, `p`, and `m` specify the parameters for a NACA airfoil.
 `m` is the maximum camber, `p` is the location of maximum camber, `c` is the coord length, and `t` is the thickness.
-Additional details on this specification can be found in [The Naca Airfoil Series](https://web.stanford.edu/~cantwell/AA200_Course_Material/The%20NACA%20airfoil%20series.pdf)
+Additional details on this specification can be found in [NACA airfoil](https://en.wikipedia.org/wiki/NACA_airfoil).
 
 - `slip` applies a slip boundary to the surface of the patch if true and a no-slip boundary condition to the surface if false.