doc: update list of re-exported symbols

libuv and zlib symbols are also purposefully re-exported by Node.js for
use in Addons.

Refs: nodejs#17444

PR-URL: nodejs#19013
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

doc/api/addons.md

@@ -34,8 +34,9 @@ involving knowledge of several components and APIs :
 
  - Node.js includes a number of other statically linked libraries including
    OpenSSL. These other libraries are located in the `deps/` directory in the
-   Node.js source tree. Only the V8 and OpenSSL symbols are purposefully
-   re-exported by Node.js and may be used to various extents by Addons.
+   Node.js source tree. Only the libuv, OpenSSL, V8 and zlib symbols are
+   purposefully re-exported by Node.js and may be used to various extents by
+   Addons.
    See [Linking to Node.js' own dependencies][] for additional information.
 
 All of the following examples are available for [download][] and may