Clarify remote require of relative modules

The docs for the `remote.require(module)` method were a little too terse for me to understand the behavior of relative module loading for `remote.require` and I had to run an experiment to understand the behavior (e.g. is the relative path relative to caller of `remote.require` or relative to some other path in the project related to the main process?).   I think this is correct but someone please double check my understanding.

Adding an example and additional explanation should help clarify this.  Feel free to edit the copy as needed.

docs/api/remote.md

@@ -140,7 +140,26 @@ The `remote` module has the following methods:
 
 * `module` String
 
-Returns `any` - The object returned by `require(module)` in the main process.
+Returns `any` - The object returned by `require(module)` in the main process.  Modules specified by their relative path will resolve relative to the entrypoint of the main process.
+
+e.g.
+
+```js
+// main process: main/index.js
+const { app, ipcMain } = require('electron')
+app.on('ready', () => {
+//...
+```
+
+```js
+// some relative module: main/foo.js
+module.exports = 'bar'
+```
+
+```js
+// renderer process: renderer/index.js
+const foo = require('electron').remote.require('./foo') // bar
+```
 
 ### `remote.getCurrentWindow()`