Dear all,
Finally, I come up with the solution for book resources content alignment justified. By default, it has left, center and right alignment. So, those who wants to see the text in mod->Book->content as jutified, please write the below CSS in your custom css inside the moodle:
.dir-ltr, .mdl-left, .dir-rtl .mdl-right {
text-align: justify;
}
Thanks,
Moodle_expert