Fix markdown

index.md

@@ -213,7 +213,7 @@ available on github. In particular, the
 [SignalToNoise](https://github.com/lsst/rubin_sim/blob/main/rubin_sim/phot_utils/signaltonoise.py)
 module calculates signal to noise ratios and limiting magnitudes (m5)
 values. Here is a
-[jupyter notebook example](https://github.com/lsst/rubin_sim_notebooks/blob/main/photometry/calculating_snr.ipynb
+[jupyter notebook example](https://github.com/lsst/rubin_sim_notebooks/blob/main/photometry/calculating_snr.ipynb)
 using this code to calculate SNR in a variety of situations.
 
 The throughput curves used for this analysis were the throughput curves in the