Point 'alt' parameter units & documentation

[noahcreany]

I want to start by saying this is an awesome package and thank you so much for developing and maintaining it - it's the best. 👍

I have a question about the expected units for the alt parameter. Obviously the lat-lon is expecting degrees according to a world geographic coordinate system (epsg: 4326?). But I have elevation in meters for my points, and I suspect that's what this parameter is expecting since the weather stations have an elevation parameter that is in meters.

I would recommend adding an additional column with the expected units to the parameters for the meteostat.Point to help reduce ambiguity and prevent erroneous data.

[clampr]

Thank you @noahcreany!

Your assumptions are correct. I created a PR which adds a "Unit" column to the parameters table: meteostat/dev#19