Update README.md

README.md

@@ -5,7 +5,7 @@ GDS scripting that's intuitive, fast, and powerful.  For Python 2 and 3.
 
 - [**Installation / requirements**](#installation--requirements)
 - [**Tutorial + examples**](https://phidl.readthedocs.io/en/latest/tutorials.html) (or [try an interactive notebook](https://mybinder.org/v2/gh/amccaugh/phidl/master?filepath=phidl_tutorial_example.ipynb))
-- [**Geometry library + function documentation**](https://phidl.readthedocs.io/)
+- [**Geometry library + function documentation**](https://phidl.readthedocs.io/en/latest/geometry_reference.html)
 - [Changelog](https://github.com/amccaugh/phidl/blob/master/CHANGELOG.md) (latest update 1.5.2 on May 19, 2021)
   - Better interactive windows for `quickplot()`! Now you can use the mousewheel/trackpad scroll to zoom in and out, and right-click or left-click to zoom to a region.
   - New `pg.gridsweep()` function, allowing for easy creation of parameter sweeps on a grid.  See [the documentation](https://phidl.readthedocs.io/en/latest/geometry_reference.html#Gridsweep) for details.