I have a text file `fileslist` containing a list of names of files, or rather relative paths to those files and their names from a certain parent directory. There is only one file per line in `fileslist`. From that parent directory I want to run a command on every single file one by one. This command should search the entire every single one of those files for a pattern, and replace it with another pattern. Each of these text files may or may not contain the pattern `College Documents`. I want to replace it with `College_Documents`. How can I do that?