Fix Link to APEBench

Hi Moeed,

I think the link to APEBench was broken. This is a quick fix!

README.md

@@ -13,7 +13,7 @@ tags:
 - advection
 - advection-diffusion
 ---
-This dataset is generated from APEBENCH [(https://github.com/tum-pbs/apebench)]. 
+This dataset is generated from [APEBench](https://github.com/tum-pbs/apebench). 
 
 It contains 128x128 grid 2D data of various PDEs with periodic initial conditions. 
 Data is already partitioned into train/val/test sets randomly.