give attribution to previous work in nc package (#1474)

Co-authored-by: Hadley Wickham <[email protected]>

NEWS.md

@@ -11,7 +11,11 @@
   `separate()` and `extract()`, featuring improved performance, greater
   consistency, a polished API, and a new approach for handling problems. They
   use stringr and supersede `extract()`, `separate()`, and `separate_rows()`
-  (#1304).
+  (#1304). 
+
+    The named character vector interface used in `separate_wider_regex()`
+    is very similar to the [nc](https://github.com/tdhock/nc) package by 
+    Toby Dylan Hocking.
 
 * `nest()` gains a `.by` argument which allows you to specify the columns to
   nest by (rather than the columns to nest, i.e. through `...`). Additionally,