add docker hub link

README.md

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 # osixia/openldap:1.1.0
 
-[![](https://badge.imagelayers.io/osixia/openldap:latest.svg)](https://imagelayers.io/?images=osixia/openldap:latest 'Get your own badge on imagelayers.io')
+[![](https://badge.imagelayers.io/osixia/openldap:latest.svg)](https://imagelayers.io/?images=osixia/openldap:latest 'Get your own badge on imagelayers.io') | [Docker Hub](https://hub.docker.com/r/osixia/openldap/) 
 
 A docker image to run OpenLDAP. Latest release: 1.1.0 / OpenLDAP 2.4.40 - [Changelog](CHANGELOG.md)