NEP: add notes about updates to NEP-18
NEP: add notes about updates to NEP-18

As discussion in GH12140

ahaldane/numpy,pizzathief/numpy,ahaldane/numpy,grlee77/numpy,simongibbons/numpy,pbrod/numpy,abalkin/numpy,simongibbons/numpy,madphysicist/numpy,numpy/numpy,jakirkham/numpy,gfyoung/numpy,rgommers/numpy,abalkin/numpy,simongibbons/numpy,anntzer/numpy,mattip/numpy,jorisvandenbossche/numpy,ahaldane/numpy,endolith/numpy,rgommers/numpy,mhvk/numpy,pdebuyl/numpy,grlee77/numpy,grlee77/numpy,shoyer/numpy,pbrod/numpy,simongibbons/numpy,WarrenWeckesser/numpy,pbrod/numpy,jakirkham/numpy,gfyoung/numpy,jakirkham/numpy,pdebuyl/numpy,endolith/numpy,anntzer/numpy,madphysicist/numpy,numpy/numpy,WarrenWeckesser/numpy,shoyer/numpy,pdebuyl/numpy,madphysicist/numpy,jakirkham/numpy,pizzathief/numpy,MSeifert04/numpy,grlee77/numpy,WarrenWeckesser/numpy,ahaldane/numpy,pizzathief/numpy,mhvk/numpy,rgommers/numpy,charris/numpy,jakirkham/numpy,shoyer/numpy,mattip/numpy,madphysicist/numpy,MSeifert04/numpy,seberg/numpy,MSeifert04/numpy,MSeifert04/numpy,mhvk/numpy,pizzathief/numpy,WarrenWeckesser/numpy,ahaldane/numpy,WarrenWeckesser/numpy,mhvk/numpy,endolith/numpy,anntzer/numpy,simongibbons/numpy,pbrod/numpy,seberg/numpy,numpy/numpy,gfyoung/numpy,charris/numpy,shoyer/numpy,MSeifert04/numpy,pbrod/numpy,seberg/numpy,jorisvandenbossche/numpy,abalkin/numpy,numpy/numpy,rgommers/numpy,seberg/numpy,anntzer/numpy,jorisvandenbossche/numpy,mhvk/numpy,grlee77/numpy,pdebuyl/numpy,jorisvandenbossche/numpy,mattip/numpy,endolith/numpy,madphysicist/numpy,jorisvandenbossche/numpy,mattip/numpy,shoyer/numpy,charris/numpy,charris/numpy,pizzathief/numpy