Update README.md with note on symlinks

README.md

@@ -66,16 +66,18 @@ export default {
 };
 ```
 
-### Usage in monorepo
+### Usage with symlinks
 
-In case you are using a monorepo, you may want to use a regular expression for `include` as the string 'node_modules' will not match if your `node_modules` is not in your current working directory (i.e. '../node_modules'). Try this:
+Symlinks are common in monorepos and are also created by the `npm link` command. Rollup with `rollup-plugin-node-resolve` resolves modules to their real paths by default. So `include` and `exclude` paths should handle real paths rather than symlinked paths (e.g. `../common/node_modules/**` instead of `node_modules/**`). You may also use a regular expression for `include` that works regardless of base path. Try this:
 
 ```
 commonjs({
   include: /node_modules/
 })
 ```
 
+Whether symlinked module paths are [realpathed](http://man7.org/linux/man-pages/man3/realpath.3.html) or preserved depends on Rollup's `preserveSymlinks` setting, which is false by default, matching Node.js' default behavior. Setting `preserveSymlinks` to true in your Rollup config will cause `import` and `export` to match based on symlinked paths instead.
+
 ### Custom named exports
 
 This plugin will attempt to create named exports, where appropriate, so you can do this...