feat : add readme

README.md

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+# Grove - Four Digital Tubes Display
+***
+## Introduction of sensor
+Grove - Four Digital Tubes Display,it can display number,and scrolling displaying.
+***
+## Usage:
+Download all the source files.
+There are four examples for user to use.
+>* **example/display_custom/display_custom.ino**.
+>* **example/display_scroll_string/display_scroll_string.ino**:Display scrolling string which longer than 4.
+>* **example/display_scroll_number/display_scroll_number.ino**:Display scrolling number which bigger than 9999.
+>* **example/display_basic/display_basic.ino**:Basic static display demo.
+
+
+----
+
+This software is written by Jerry Yip for seeed studio and is licensed under [The MIT License](http://opensource.org/licenses/mit-license.php). Check License.txt for more information.<br>
+
+Contributing to this software is warmly welcomed. You can do this basically by<br>
+[forking](https://help.github.com/articles/fork-a-repo), committing modifications and then [pulling requests](https://help.github.com/articles/using-pull-requests) (follow the links above<br>
+for operating guide). Adding change log and your contact into file header is encouraged.<br>
+Thanks for your contribution.
+
+Seeed Studio is an open hardware facilitation company based in Shenzhen, China. <br>
+Benefiting from local manufacture power and convenient global logistic system, <br>
+we integrate resources to serve new era of innovation. Seeed also works with <br>
+global distributors and partners to push open hardware movement.<br>
+
+
+[![Analytics](https://ga-beacon.appspot.com/UA-46589105-3/grove-led-matrix-driver-ht16k33)](https://github.com/igrigorik/ga-beacon)