DOC: Spell out note for `dstack`
DOC: Spell out note for `dstack`

This adds to the documentation on `dstack` the notes from `hstack` and `vstack` about dimensionality requirements.
simongibbons/numpy,pizzathief/numpy,abalkin/numpy,numpy/numpy,simongibbons/numpy,chatcannon/numpy,WarrenWeckesser/numpy,endolith/numpy,shoyer/numpy,bringingheavendown/numpy,MSeifert04/numpy,WarrenWeckesser/numpy,anntzer/numpy,rgommers/numpy,Eric89GXL/numpy,jakirkham/numpy,mhvk/numpy,seberg/numpy,b-carter/numpy,seberg/numpy,madphysicist/numpy,MSeifert04/numpy,abalkin/numpy,bringingheavendown/numpy,jorisvandenbossche/numpy,grlee77/numpy,shoyer/numpy,gfyoung/numpy,chatcannon/numpy,pizzathief/numpy,jakirkham/numpy,shoyer/numpy,ahaldane/numpy,WarrenWeckesser/numpy,pdebuyl/numpy,pbrod/numpy,seberg/numpy,rgommers/numpy,numpy/numpy,MSeifert04/numpy,ahaldane/numpy,pizzathief/numpy,charris/numpy,jakirkham/numpy,jorisvandenbossche/numpy,numpy/numpy,pbrod/numpy,solarjoe/numpy,mhvk/numpy,jorisvandenbossche/numpy,pizzathief/numpy,Eric89GXL/numpy,pdebuyl/numpy,WarrenWeckesser/numpy,abalkin/numpy,Eric89GXL/numpy,endolith/numpy,behzadnouri/numpy,pbrod/numpy,rgommers/numpy,grlee77/numpy,jorisvandenbossche/numpy,anntzer/numpy,behzadnouri/numpy,solarjoe/numpy,tynn/numpy,endolith/numpy,pbrod/numpy,simongibbons/numpy,ahaldane/numpy,pdebuyl/numpy,jakirkham/numpy,behzadnouri/numpy,solarjoe/numpy,tynn/numpy,tynn/numpy,simongibbons/numpy,anntzer/numpy,mattip/numpy,mattip/numpy,gfyoung/numpy,grlee77/numpy,b-carter/numpy,pizzathief/numpy,MSeifert04/numpy,mhvk/numpy,mhvk/numpy,MSeifert04/numpy,charris/numpy,jakirkham/numpy,charris/numpy,WarrenWeckesser/numpy,madphysicist/numpy,madphysicist/numpy,grlee77/numpy,mhvk/numpy,jorisvandenbossche/numpy,bringingheavendown/numpy,pbrod/numpy,Eric89GXL/numpy,b-carter/numpy,numpy/numpy,ahaldane/numpy,anntzer/numpy,shoyer/numpy,grlee77/numpy,pdebuyl/numpy,madphysicist/numpy,mattip/numpy,shoyer/numpy,chatcannon/numpy,gfyoung/numpy,madphysicist/numpy,rgommers/numpy,mattip/numpy,seberg/numpy,charris/numpy,endolith/numpy,simongibbons/numpy,ahaldane/numpy