Approaches i can follow to add a general message inside my create and edit list forms?

I have a team site collection , which have 6 custom lists. now our customer ask us to add a message when users create/edit list items , the purpose of the message is to explain what does the "*" means,, something as follow:-

now i find this appraoch:-

1- inside the 6 custom lists to edit their Create/Edit forms.

2- this can be done by going to the Create/Edit forms >> Edit Page.

3- then add a "Content Editor" web part.

4- inside the "Content Editor" web part to define a Content Link as follow,which reference a .txt file:-

5- then inside the .txt file to add a message text :-

<spanstyle="color:red"> * Represents Mandatory Fields</span>

is this case i can manage the message from one place (.txt file), and even if i save my site as template and create a new sites based on the template,, the new sites will benefit from this also.. but can anyone adivce if my above appraoch is valid ? or there is another way to allow my Create/Edit forms to explain what does "*" means ? using JSLINK or other approaches ?

Thanks