$ sudo apt-get update
$ sudo apt-get install jmagick6-docs 

jmagick6-docs is installed in your system.

Make ensure the jmagick6-docs package were installed using the commands given below,

$ sudo dpkg-query -l | grep jmagick6-docs *

You will get with jmagick6-docs package name, version, architecture and description in a table

jmagick6-docs package basic information: