You should require entries in the directory to be made in alphabetical order
Without regular merges, the pull requests pile up.
For example there is currently 3 pull requests and they all modify the same line, because everyone just adds their entry to the end of the list:
These 3 pull requests all conflict.
If you order the directory alphabetically and require that new pull requests also add lines in alphabetical order, then the chances of multiple pull requests conflicting with each other will be greatly reduced.