fix typo in col-refs.md (#277)

correct the section name to that shown in the screenshot, also confirmed the correct name in production Grist UI

help/col-refs.md

@@ -82,7 +82,7 @@ doesn't exist in the `Clients` table:
 
 A big benefit of reference columns is that they allow you to easily bring in multiple columns from
 the underlying table. In our example, if you wanted to bring in `$Client.Contact` to the `Projects`
-table, you can just select the `Contact` column from the `Add Reference Columns` section and it will be
+table, you can just select the `Contact` column from the `Add Referenced Columns` section and it will be
 automatically added to the `Projects` table:
 
 ![Additional columns inserted](images/column-ref-other-columns.png)
@@ -175,4 +175,4 @@ To view a record's unique ID, add a new column with the formula = [`$id`](formul
 
 We can see that the value in the Full Name column for the record with Row ID =`2` is `Dowbakin, Daniella`. If we revert back to our original settings for the Instructor column of the Classes table, where `Full Name` was selected under Show Column, we see that the Full Name value associated with `Staff[2]` is `Dowbakin, Daniella`.
 
-*![columns-reference-explanation-fullname](images/columns/columns-reference-explanation-fullname.png)*
+*![columns-reference-explanation-fullname](images/columns/columns-reference-explanation-fullname.png)*