Need help adding an ability with XML

[DeepSoul]

I want to add to the leader ability of an existing modded civ: +1 faith on farms adjacent to a holy site. What's the code for it? I understand enough to add segments to existing code when I'm given all the names and variables. I attached the file I want to add it to in case you need to see how it's written first.

 

[DeckerdJames]

I don't know, because I am still trying to understand too, but the stepwell for India adds +1 faith if adjacent to holy sites, along with some other bonuses. You could start there. The stepwell is in the improvements.xml in the Base/Assets/Gameplay/Data. That improvement might, at least, give some clues.