Hi Nicolas,
Sorry, but i have no code experience so if there is no way of putting button on my admin text editor in backend to automatically add this "read more" button on front end, then I will have to wait until I can review more on the code side before I try to do it manually. The only reason I posted my question about this was that I read on your tutorial Product and Variant Add/Edit THIS under the Description section:
Description : The description of the product. You can insert here joomla content tags and they will be replaced on the front end by their content plugins. If you activate the "read more" option of the configuration, you should see an additional button on the bottom of the description HTML editor allowing you to add a read more tag in the description ( alternatively, you can use the HTML tag <hr id="system-readmore" /> if you want to add the read more manually ). The text before the read more tag would be displayed on the listings of products displayed with the item box layout "image and description" while the full text would be displayed on the product page.
So I thought there must be a plugin to add a button to the editor. This is what i was trying to activate. You might need to revise the above doc if there is no "read more" option to activate.
Regardless, I tried to follow your post above and hacked the two files as instructed [see pics], however, I must be missing something further steps to finish the job... I also tried to insert the above tag [<hr id="system-readmore" />] into my text editor and instead of displaying a read more button on the category listing page, it displayed the button directly on the editor page and html code on front end. To make matters worse, I am still a bit confused on all the options for categories and products listings and could be making some errors there as well.
Conclusion: If there is no back-end button to add the front end 'read more' button, then I will hold off on this until I study more on the code side and the categories listings before I attempt to do it manually.
ps: If you see any major mistakes in the code i added [pics below] please let me know so I can delete it.
Thanks again and sorry for my lack of experience here.
Regards
Scott