This change is adding required configuration in neutron.conf
to set the lock_path parameter, which was missing in
compute-install-ubuntu.rst
Change-Id: If090bdf060dfe21d11b1a5dfd010dc8167d9e45e
Closes-Bug: #1796976
(cherry picked from commit f4d438019e3bd2f9b6c64badb9533168e583d8af)