gnrc_netapi: move author tag into file context
gnrc_netapi: move author tag into file context

Otherwise, the authorship is associated with `GNRC_NETAPI_MSG_TYPE_RCV`
in the rendered doc.

authmillenon/RIOT,yogo1212/RIOT,BytesGalore/RIOT,josephnoir/RIOT,basilfx/RIOT,cladmi/RIOT,aeneby/RIOT,gebart/RIOT,smlng/RIOT,A-Paul/RIOT,kYc0o/RIOT,kYc0o/RIOT,BytesGalore/RIOT,aeneby/RIOT,RIOT-OS/RIOT,josephnoir/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,lazytech-org/RIOT,OTAkeys/RIOT,smlng/RIOT,yogo1212/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,rfuentess/RIOT,miri64/RIOT,rfuentess/RIOT,authmillenon/RIOT,miri64/RIOT,x3ro/RIOT,RIOT-OS/RIOT,basilfx/RIOT,A-Paul/RIOT,mfrey/RIOT,aeneby/RIOT,mtausig/RIOT,kYc0o/RIOT,toonst/RIOT,smlng/RIOT,x3ro/RIOT,x3ro/RIOT,A-Paul/RIOT,toonst/RIOT,yogo1212/RIOT,mfrey/RIOT,basilfx/RIOT,gebart/RIOT,ant9000/RIOT,mfrey/RIOT,biboc/RIOT,OTAkeys/RIOT,cladmi/RIOT,yogo1212/RIOT,josephnoir/RIOT,miri64/RIOT,lazytech-org/RIOT,mfrey/RIOT,RIOT-OS/RIOT,josephnoir/RIOT,toonst/RIOT,kaspar030/RIOT,kaspar030/RIOT,ant9000/RIOT,lazytech-org/RIOT,rfuentess/RIOT,A-Paul/RIOT,kYc0o/RIOT,OTAkeys/RIOT,biboc/RIOT,OTAkeys/RIOT,ant9000/RIOT,cladmi/RIOT,biboc/RIOT,mtausig/RIOT,BytesGalore/RIOT,x3ro/RIOT,x3ro/RIOT,kYc0o/RIOT,jasonatran/RIOT,gebart/RIOT,BytesGalore/RIOT,biboc/RIOT,smlng/RIOT,miri64/RIOT,rfuentess/RIOT,jasonatran/RIOT,OlegHahm/RIOT,authmillenon/RIOT,mfrey/RIOT,OlegHahm/RIOT,ant9000/RIOT,authmillenon/RIOT,BytesGalore/RIOT,authmillenon/RIOT,cladmi/RIOT,toonst/RIOT,OlegHahm/RIOT,mtausig/RIOT,rfuentess/RIOT,lazytech-org/RIOT,OlegHahm/RIOT,biboc/RIOT,jasonatran/RIOT,ant9000/RIOT,kaspar030/RIOT,smlng/RIOT,aeneby/RIOT,cladmi/RIOT,mtausig/RIOT,basilfx/RIOT,authmillenon/RIOT,gebart/RIOT,miri64/RIOT,toonst/RIOT,A-Paul/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,josephnoir/RIOT,mtausig/RIOT,gebart/RIOT,jasonatran/RIOT,lazytech-org/RIOT,aeneby/RIOT,jasonatran/RIOT,kaspar030/RIOT,basilfx/RIOT,yogo1212/RIOT