Update README.md

From vercel#109

Author: rastiqdev

README.md

@@ -57,6 +57,21 @@ Since Hazel routes all the traffic for downloading the actual application files
 
 As an example, check out the [latest Hyper release](https://api.github.com/repos/vercel/hyper/releases/latest) and search for `mac.zip`. You'll find a release containing a sub property named `download_count` with the amount of downloads as its value.
 
+## Release Files Naming And Extension
+
+We find and cache releases for each platform by the file name and extension. it may be obvious but can save quite some times for those who just getting started.
+
+As you can see in [platform.js](https://github.com/vercel/hazel/blob/master/lib/platform.js) and [aliases.js](https://github.com/vercel/hazel/blob/master/lib/aliases.js), for each OS, the extensions are expected as below:
+
+| OS                             | :platform           | .Extension                                              |
+|--------------------------------|---------------------|---------------------------------------------------------|
+| Windows                        | win32, windows, win | .exe                                                    |
+| macOS                          | dmg                 | .dmg                                                    |
+| macOS                          | darwin              | .zip (only if the file name contains "mac" or "darwin") |
+| Linux with RPM package manager | fedora              | .rpm                                                    |
+| Linux with DEB package manager | debian              | .deb                                                    |
+| Linux                          | appimage            | .AppImage                                               |
+
 ## Routes
 
 ### /