Fix docstring [ci skip]

spacy/pipeline/pipe.pyx

@@ -32,7 +32,9 @@ class Pipe:
         raise NotImplementedError
 
     def __call__(self, Doc doc):
-        """Add context-sensitive embeddings to the Doc.tensor attribute.
+        """Apply the pipe to one document. The document is modified in place,
+        and returned. This usually happens under the hood when the nlp object
+        is called on a text and all components are applied to the Doc.
 
         docs (Doc): The Doc to preocess.
         RETURNS (Doc): The processed Doc.