[sfSolrPlugin] fix class name in README file
[sfSolrPlugin] fix class name in README file

git-svn-id: 3e4e6e26c3323712072b5e994d1dad179984f868@29409 ee427ae8-e902-0410-961c-c3ed070cd9f9

rande/sfSolrPlugin,rande/sfSolrPlugin