Update documentation: objective-weights and objective-measures ignores first column

[wmodes]

Currently, the documentation doesn't mention how the first column of the data.csv file is handled with regard to objective-weights and objective-measures.

After some experimentation, I concluded that the first objective-weight and first objective-measure in the list apply to the second column. If true, please reflect that in the documentation. Thank you.

It would also be useful to see an example in the docs of using objective-weights and objective-measures.