doc release: describe more for creating tar.gz
doc release: describe more for creating tar.gz

yoku0825/mroonga,naoa/mroonga,naoa/mroonga,naoa/mroonga,naoa/mroonga,yoku0825/mroonga,yoku0825/mroonga,naoa/mroonga,mroonga/mroonga,mroonga/mroonga,naoa/mroonga,mroonga/mroonga,yoku0825/mroonga,yoku0825/mroonga,mroonga/mroonga,yoku0825/mroonga