javalang.tokenizer.LexerError when parsing input files with escaping characters

[darthdaver]

Improve the README.md instructions to understand how the input file should be generated.

Test prefixes and focal methods can contain strings with double quote characters. Escaping characters lead to javalang.tokenizer.LexerError. After attempts, I realized a double double quote"" must be used to manage this case.
I would suggest to add information about the input somewhere in the README.md