typo.

git-svn-id: http://root.cern.ch/svn/root/trunk@8793 27541ba8-7e3a-0410-8455-c3a389f83636

zip/README

 The compression package "zlib" is part of the zip directory. The original tar 
 file can be downloaded from : http://www.zlib.org 
 
-Only the useful code as been extracted from this tar file. It consists of: 
+Only the useful code has been extracted from this tar file. It consists of: 
 
  zip/inc:
    crc32.h deflate.h inffast.h inffixed.h inflate.h