fix README

README.md

@@ -365,12 +365,12 @@ on Heroku and provides the prediction for any crystal within seconds.
 <a name="limitations"></a>
 # Known limitations
 
-- `isolated atoms` error. This error occurs when using the given cutoff in the model (4A in
+- `isolated atoms` error. This error occurs when using the given cutoff in the model (4A for
 2018 models and 5A for 2019 models), the crystal structure contains isolated atoms, i.e., 
 no neighboring atoms are within the distance of `cutoff`. Most of the time, we can just 
 discard the structure, since we found that those structures tend to have a high energy above 
-hull (less stable). If you find this error becomes an essential issue for a particular problem, 
-feel free to email us and we will consider release a new model with increased cutoff. 
+hull (less stable). If you think this error is an essential issue for a particular problem, 
+please feel free to email us and we will consider releasing a new model with increased cutoff. 
 
 <a name="references"></a>
 # References