adding netcdf4-python

[gonzigaran]

Project name: netcdf4-python

Project website/repository: https://github.com/Unidata/netcdf4-python

License: https://github.com/Unidata/netcdf4-python/blob/master/COPYING

Checklist for new projects:

• [x] The project is open-source and accessible.
• [x] Searched the existing entries to make sure this is not a duplicate.
• [x] Contains only a single addition (make separate PRs if adding more than one).
• [x] Added the link to the bottom of the relevant category.
• [x] Add icon from the media/icon/ folder if applicable (like ![Python](media/icon/python.png) ).
• [x] Created a new category only if necessary.
• [x] Checked spelling and grammar.
• [x] Removed trailing whitespace and periods.
• [x] Confirm the dash – is not a minus -.
• [x] Used title-casing (AP style) for project name.