Merge pull request #3233 from myverdict/patch-17

Update part4d.md

Author: mluukkai

src/content/4/en/part4d.md

@@ -412,7 +412,7 @@ Modify adding new blogs so that it is only possible if a valid token is sent wit
 
 #### 4.20*: bloglist expansion, step8
 
-[This example](/en/part4/token_authentication) from part 4 shows taking the token from the header with the _getTokenFrom_ helper function.
+[This example](/en/part4/token_authentication) from part 4 shows taking the token from the header with the _getTokenFrom_ helper function in <i>controllers/blogs.js</i>.
 
 If you used the same solution, refactor taking the token to a [middleware](/en/part3/node_js_and_express#middleware). The middleware should take the token from the <i>Authorization</i> header and place it into the <i>token</i> field of the <i>request</i> object.