Fix grammar

README.md

@@ -71,7 +71,7 @@ whereas the following abbreviations are used:
 | sh | Signifies that attention heads are shared | 
 | skv | Signifies that key-values projection matrices are tied | 
 
-If a model checkpoint has no specific, *el* or *dl* than both the number of encoder- and decoder layers correspond to *nl*.
+If a model checkpoint has no specific *el* or *dl*, then both of the numbers of encoder and decoder layers correspond to *nl*.
 
 ## Pre-Training