Fix long names

[jesusff]

I open this PR to fix some problems reported by @ozanmert:

1. All pressure level u winds such as ua300, ua 2000... Have standard and long names "eastward wind" with no other detail... Is this intended?
2. There are some inconsistencies between variable names and their long names, such as: The long name of ua300m is "eastward wind at 250m"... I guess this should be corrected?

[jesusff]

Thank you, Ozan

Standard names must follow those defined by CF, and these represent the physical quantity. Other aspects, such as the level, are represented by other metadata of the variable (such as a scalar coordinate variable representing the pressure level). So standard_names are OK even if repeated for many different variables.

Long names are not critical as these are just free text descriptions. However, you spotted a clear inconsistency between the variable and the corresponding metadata, so this should be fixed. I let the PR open, just in case you found some others.

Long names without much detail are no problem, in principle. For pressure level data we could include the level explicitly, though. E.g. in CMIP6 they do include it: https://github.com/PCMDI/cmip6-cmor-tables/blob/80d2e4b606555720630a61389cfe3b5cb8f43746/Tables/CMIP6_6hrPlev.json#L312

@larsbuntemeyer @gnikulin what do you think?

[larsbuntemeyer]

Thanks for catching theses inconsistencies! Yes, in CMIP6, pressure levels were published often as 3D variables with a plev coordinates which is why those pressure level coordinates were missing in the long name. But i think, it would make sense to add the pressure level value to the long name which would also be consistent with the long names of variables at certain height levels (which also contain the height value).

[larsbuntemeyer]

I can add this into this PR.

[larsbuntemeyer]

I fix this in #41 after restructuring.

[larsbuntemeyer]

Fixed in #41