It's right there in front of you hah. But menu files can be a bit confusing at first since there's not a ton of documentation. You need to be looking in raw>ui for them, you want main.menu.
The game puts a generic phrase in the .menu code and then spells out the strings in the .str files. This is so you can have multiple languages that all connect to one generic phrase in the menu file.
So you can either change just the strings (you don't even have to edit the menu files) or you can replace the string reference in the code with text inside quotes of whatever you want. For example, you could go into main.menu and change the strings you want, such as "@MENU_MAIN_MENU" to "My Text Here" or you can find the string file named menu.str (it's always the first word after the "@" symbol and then within menu.str you find MAIN_MENU and you can enter the appropriate text that you want.
