Fix broken links in FAQ 26

[lprivette]

For FAQ 26, Some of the links don't work: a) https://www.epa.gov/safewater/privatewells/index2.html https://www.epa.gov/safewater/privatewells/whereyoulive_state.html. Both of these SHOULD BE UPDATED AND A SINGLE LINK: https://www.epa.gov/privatewells b) National FarmASyst/HomeASyst Program https://www.uwex.edu/homeasyst/index.html REPLACE WITH THIS URL https://extension.psu.edu/programs/nutrient-management/farm-a-syst c) U. S. Department of Agriculture, Cooperative State Research, Education, and Extension Service (CREES) National Water Program, Drinking Water & Human Health https://www.usawaterquality.org/themes/health/default.html REMOVE OLD LINK - just drop c completely d) National Ground Water Association https://www.ngwa.org and https://www.wellowner.org CHANGE THE NGWA link To: http://www.ngwa.org/Pages/default.aspx