Update instructions.

README.md

@@ -1,6 +1,8 @@
 Preview Github README.md
 ========================
 
+The preview mimics repo homepage in Github.
+
 ## Requirements ##
 * PHP 5.3+
 * curl enabled
@@ -9,6 +11,27 @@ Preview Github README.md
 ## How to use ##
 You have project that need to be published onto Github and you're not
 sure about how the README.md will render in your repository's homepage.
+
+### Using CLI ###
+
+```
+$ ./preview_github_readme README.md
+```
+
+or you can pipe it to browser:
+
+```
+$ ./preview_github_readme README.md | browser
+````
+
+In daily use, it's worth to alias this long script's name:
+
+```
+alias gmd='/path/to/cloned-repo/preview_github_readme'
+```
+
+### Using webserver ####
+
 Assuming your local development is accessible via `http://localhost/`
 and you're cloning this preview scripts into the docroot of your localhost.
 Now you can preview your local README.md:
@@ -25,7 +48,9 @@ php -S localhost:8080
 
 and open above url with specified port.
 
-`preview_github_readme.php` looks for passed arg `?file=/path/to/readme.md` and
+## How it Works
+
+`preview_github_readme.php` looks for readme file and
 if the file exists, send it to Github Markdown's API, otherwise lookup README.md,
 Readme.md, or readme.md file in root directory.