更新《跟我一起写 Makefile》

#803

README.md

@@ -358,7 +358,7 @@
 * [100个gcc小技巧](https://github.com/hellogcc/100-gcc-tips/blob/master/src/index.md)
 * [ZMQ 指南](https://github.com/anjuke/zguide-cn)
 * [How to Think Like a Computer Scientist](http://www.ituring.com.cn/book/1203) (中英文版)
-* [跟我一起写Makefile(PDF)](http://scc.qibebt.cas.cn/docs/linux/base/%B8%FA%CE%D2%D2%BB%C6%F0%D0%B4Makefile-%B3%C2%F0%A9.pdf)
+* [跟我一起写 Makefile](https://github.com/seisman/how-to-write-makefile)
 * [GNU make中文手册](http://www.yayu.org/book/gnu_make/)
 * [GNU make 指南](http://docs.huihoo.com/gnu/linux/gmake.html)
 * [Google C++ 风格指南](http://zh-google-styleguide.readthedocs.org/en/latest/google-cpp-styleguide/contents/)