readme: change link to failover manual to github wiki
readme: change link to failover manual to github wiki

harnesscloud/xtreemfs,jswrenn/xtreemfs,kleingeist/xtreemfs,kleingeist/xtreemfs,harnesscloud/xtreemfs,kleingeist/xtreemfs,rbaerzib/xtreemfs,jswrenn/xtreemfs,kleingeist/xtreemfs,rbaerzib/xtreemfs,rbaerzib/xtreemfs,harnesscloud/xtreemfs,rbaerzib/xtreemfs,rbaerzib/xtreemfs,jswrenn/xtreemfs,jswrenn/xtreemfs,harnesscloud/xtreemfs,harnesscloud/xtreemfs,harnesscloud/xtreemfs,harnesscloud/xtreemfs,kleingeist/xtreemfs,harnesscloud/xtreemfs,jswrenn/xtreemfs,jswrenn/xtreemfs,jswrenn/xtreemfs,jswrenn/xtreemfs,kleingeist/xtreemfs,rbaerzib/xtreemfs,rbaerzib/xtreemfs,kleingeist/xtreemfs,rbaerzib/xtreemfs,kleingeist/xtreemfs