List all the possible folders for Linux.

Linux has several folders, depending on who is using the Linux install.  On our systems it could be any one of those depending on the user and what software they prefer to use, they all have the React plugin however, each one sits in a different folder.  I prefer Chrome because of Netflix, she prefers Chromium and we also have Chrome Beta available.

docs/tutorial/devtools-extension.md

@@ -16,7 +16,11 @@ Using the [React Developer Tools][react-devtools] as example:
    string like `fmkadmapgofadopljbjfkapdkoienihi`.
 1. Find out filesystem location used by Chrome for storing extensions:
    * on Windows it is `%LOCALAPPDATA%\Google\Chrome\User Data\Default\Extensions`;
-   * on Linux it is `~/.config/google-chrome/Default/Extensions/`;
+   * on Linux it could be:
+     * `~/.config/google-chrome/Default/Extensions/`
+     * `~/.config/google-chrome-beta/Default/Extensions/`
+     * `~/.config/google-chrome-canary/Default/Extensions/`
+     * `~/.config/chromium/Default/Extensions/`
    * on OS X it is `~/Library/Application Support/Google/Chrome/Default/Extensions`.
 1. Pass the location of the extension to `BrowserWindow.addDevToolsExtension`
    API, for the React Developer Tools, it is something like: