add reference links to readme
add reference links to readme

recoilme/lmdbjni,placrosse/lmdbjni,recoilme/lmdbjni,placrosse/lmdbjni,headuck/lmdbjni,recoilme/lmdbjni,deephacks/lmdbjni,deephacks/lmdbjni,headuck/lmdbjni,deephacks/lmdbjni,placrosse/lmdbjni,headuck/lmdbjni