unistd::setgroups: Tweak comment about discouraged use of function

Author: JayH5

src/unistd.rs

@@ -1028,7 +1028,9 @@ pub fn getgroups() -> Result<Vec<Gid>> {
 /// Set the list of supplementary group IDs for the calling process.
 ///
 /// *Note:* On macOS, `getgroups()` may not return the same group list set by
-/// calling `setgroups()`. Apple discourages the use of `setgroups()`.
+/// calling `setgroups()`. The use of `setgroups()` on macOS is 'highly
+/// discouraged' by Apple. Developers are referred to the `opendirectoryd`
+/// daemon and its set of APIs.
 ///
 /// [Further reading](http://man7.org/linux/man-pages/man2/getgroups.2.html)
 ///