File/String usage in documentation

[I3ck]

Within the documentation most parameters are described as file. But it seems like the parameters are actually strings (at least in many cases).
I think it makes sense to update the documentation accordingly.

[bmwill]

Yes I can see how that would be slightly confusing. The intent of the library is to provide the functionality for diffing/merging files but in order to be more flexible all of the interfaces work on borrowed strings instead of a std::fs::File type. The expected usage would be to first read a file into a String and then use this library. I'll try and make suitable adjustments to the documentation to reflect this