Methods to search for a book
If the user chooses that option he should be asked of he wants to search for it using the books title (or part of it) or using the name of one of the authors (or part of the name)
Depending on that search the user should go through the Library.txt file and print all the books matching that certain criteria. And if none was found an appropriate message should be printed. (the search needs to be case sensitive as the user can search using lower case letters or upper case one)