Update link in Theory section of documentation

[andermi]

mbari_wec/docs/docs/theory.md

Line 63 in 67d960d

- Free-Surface Hydrodynamic Coefficients and Impulse Response Functions can be found <a href="https://www.google.com/") target="_blank">here</a>:

Where was this supposed to point?

[hamilton8415]

Ha, just search the internet and you will find them... OK, I will fix that. -- Andy