Update outdated documentation

[hoshsadiq]

Some of the documentation is outdated. This should be updated.

From a PM:

Another thing that should be documented is that the CSV output doesn't show anything but: tvg-id group-title tvg-name duration tvg-logo uri

And that the variables are case sensitive. I think they may have been shown in some documentation with a capital letter when they are all lower case. Needs confirming, but it does make sense