some articles about memory allocation

doc/malloc.md

@@ -1 +1,3 @@
 [参考链接1](https://blog.codinglabs.org/articles/a-malloc-tutorial.html#212-%E9%A1%B5%E4%B8%8E%E5%9C%B0%E5%9D%80%E6%9E%84%E6%88%90)
+[malloc的glibc实现](https://repo.or.cz/glibc.git/blob/HEAD:/malloc/malloc.c)
+[How the kernel manage your memory](https://manybutfinite.com/post/how-the-kernel-manages-your-memory/)