update link to eigen docs

Author: tomeichlersmith

README.md

@@ -48,7 +48,7 @@ Software Package | Version | Construction Process
 [nlohmann/json](https://json.nlohmann.me/) | 3.11.3 | From Ubuntu Repos
 [ROOT](https://root.cern.ch/) | 6.34.10 | Built from source
 [Geant4](https://geant4.web.cern.ch/) | [LDMX.10.2.3\_v0.6](https://github.com/LDMX-Software/geant4/tree/LDMX.10.2.3_v0.6) | Built from source
-[Eigen](https://eigen.tuxfamily.org/index.php?title=Main_Page) | 3.4.0 | Built from source
+[Eigen](https://eigen.tuxfamily.org) | 3.4.0 | Built from source
 [HEPMC3](https://hepmc.web.cern.ch) | 3.3.0 | Built from source
 [GENIE](http://www.genie-mc.org/) Generator | [3.04.02-ldmx](https://github.com/wesketchum/Generator/releases/tag/R-3_04_02-ldmx) | Built from source
 [GENIE](http://www.genie-mc.org/) Reweight | 1.04.00 | Built from Source