docs: clarify nodesDir accepts an array of paths (#433)

The configuration reference only mentioned "a directory", but the
runtime has accepted an array of paths since 0.7.0 (April 2014) -
verified against localfilesystem.js in node-red/node-red, which
normalizes the setting to an array either way. Companion fix to the
settings.js comment in node-red/node-red#5925.

Fixes node-red/node-red#1131

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

Author: Bryandero98

docs/user-guide/runtime/configuration.md

@@ -26,10 +26,11 @@ userDir
   library data. Default: `$HOME/.node-red`
 
 nodesDir
-: a directory to search for additional installed nodes. Node-RED searches the `nodes`
-  directory under the *userDir* directory. This property allows an additional directory
-  to be searched, so that nodes can be installed outside of the Node-RED install
-  structure. Default: `$HOME/.node-red/nodes`
+: one or more directories to search for additional installed nodes, given as either a
+  single string or an array of strings. Node-RED searches the `nodes` directory under
+  the *userDir* directory. This property allows additional directories to be searched,
+  so that nodes can be installed outside of the Node-RED install structure.
+  Default: `$HOME/.node-red/nodes`
 
 uiHost
 : the interface to listen for connections on. Default: `0.0.0.0` -