Citation update

Citation updated for consistency:

• Added CITATION file
• Update README citation
• Update vignette emodnetwfs citation

First stable release

This is the first stable release of the EMODnetWFS package. Features included:

• See the EMODnet Web Feature Service endpoints (tibble EMODnetWFS::emodnet_wfs)
• Create a WFS client using the ows4r library (EMODnetWFS::emodnet_init_wfs_client())
• Perform getCapabilities request, returned as a tibble (EMODnetWFS::emodnet_get_wfs_info())
• Perform getFeatures request on different EMODnet lots. Response as a sf object. Can change the CRS on the client side (EMODnetWFS::emodnet_get_layers())
• Perform getCapabilities request on all EMODnet lots. This is experimental (EMODnetWFS::emodnet_get_all_wfs_info())