README文件中有这段文字：
   There are various README files in the Documentation/ subdirectory:
   these typically contain kernel-specific installation notes for some
   drivers for example. See Documentation/00-INDEX for a list of what
   is contained in each file.  Please read the Changes file, as it
   contains information about the problems, which may result by upgrading
   your kernel.
  
   在每个子目录下面都有README文件，包含来内核安装的提示，比如某些驱动。看一下“Documentation/00-INDEX”
   这个子目录，里面列出来每个文件。
   于是我跟着进去找到它“~/Documentation/00-INDEX“。果不其然，这个文件是一个“全局”文件，里面描述了
   Documentation目录下面的这些文件所干嘛的，起码了解了一部分吧


This is a brief list of all the files in ./linux/Documentation and what
they contain.
 以下就不列出，请参考Documentation/00-INDEX