title: How to install pgcrypto module on a postgres DB
body: <p>I have Postgres version 10.5 from the docker hub and don't know how to install the pgcrypto module. 
  In <strong>/usr/lib/postgresql/10/lib#</strong> there is a <strong>pgcrypto.so</strong> file.
  What to do with that file? I can't find documentation about it, thanks for your help!</p>