Link Fields Options with Custom Scripts in the Library Management Tutorial

I decided to follow the ERPNext tutorial to better understand the system and I have been blown away by its power.
While going through the manual, I got stuck while creating a link field for the articles and member to extract article name and first name.

This really bothered me because up to this point, it had been clock work. What could I be doing wrong? arhhhh.
I think reference to custom script should have come earlier to explain the weird behavior in preparation for further understanding but I guess, this is a bit of self-learning and that way you don’t forget.

I even removed the option parameter (article.article_name for the read only field and it still works with the custom script present. I was quite surprised. My questions are…

Does applying the option parameter ONLY work for the read only field? It didn’t work for me.
Do I need to create a custom script for this to work? It was not mentioned in the manual.

Finally, can I contribute to the manual if some of these observations should have been included? I also noticed some typos in the manual that did not affect the message in any way but it would be good to contribute in any way I can to this awesome project.

I would appreciate clarifications on the link field observation. it still kinda works unusually.will update as I complete the tutorial. maybe I posted this too early.

Thanks so much for your help all.