Update README.md

Author: spacetimeengineer

README.md

@@ -302,3 +302,8 @@ This is a measure of how much two initial paralell geodesic paths will deviate o
 ![equation](https://latex.codecogs.com/png.latex?%5Cdpi%7B100%7D%20%5Chuge%20%5Cfrac%7Bd%5E%7B2%7D%5Cxi%5E%7B%5Clambda%7D%7D%7Bdt%5E%7B2%7D%7D%3D-%5C%3BR%5E%7B%5Clambda%7D_%7B%5Cmu%5Cnu%5Cell%7D%5Cfrac%7Bdx%5E%7B%5Cmu%7D%7D%7Bdt%7D%5Cfrac%7Bdx%5E%7B%5Cnu%7D%7D%7Bdt%7D%5Cxi%5E%7B%5Cell%7D)
 
     >>> spacetime.print_separation_geodesic_acceleration(0)
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