Fix reference to osx-docbook-register in manual/README
Fix reference to osx-docbook-register in manual/README

Fixed a typo in the readme of the manual,
where osx-register-docbook was referenced,
whereas the filename is actually osx-docbook-register.

HuangLS/neo4j,HuangLS/neo4j,HuangLS/neo4j,HuangLS/neo4j,HuangLS/neo4j