Fix of doc for manual install
Fix of doc for manual install


Former-commit-id: c17180ffce23191caa2f0e47ea010a4e26103352
clab/cnn,clab/dynet,xunzhang/dynet,shuheik/dynet,clab/cnn,clab/dynet,shuheik/dynet,clab/dynet,danielhers/dynet,clab/dynet,chunyang-wen/dynet,shuheik/dynet,danielhers/dynet,xunzhang/dynet,chunyang-wen/dynet,chunyang-wen/dynet,shuheik/dynet,clab/cnn,shuheik/dynet,danielhers/dynet,xunzhang/dynet,clab/dynet,shuheik/dynet,danielhers/dynet,danielhers/dynet,xunzhang/dynet,chunyang-wen/dynet,clab/dynet,danielhers/dynet,clab/dynet,danielhers/dynet,shuheik/dynet