8552 doc clip none (#8558)
8552 doc clip none (#8558)

* documenting behaviour of passing `None` to upper or lower interval bounds in `clip()`

* doc: specifying that not more than one of formal parameters `a_min` and `a_max` may be none

WarrenWeckesser/numpy,numpy/numpy,jorisvandenbossche/numpy,simongibbons/numpy,ahaldane/numpy,pbrod/numpy,jakirkham/numpy,simongibbons/numpy,numpy/numpy,chatcannon/numpy,rgommers/numpy,mhvk/numpy,WarrenWeckesser/numpy,b-carter/numpy,endolith/numpy,Eric89GXL/numpy,behzadnouri/numpy,Eric89GXL/numpy,ahaldane/numpy,rgommers/numpy,jorisvandenbossche/numpy,pizzathief/numpy,anntzer/numpy,abalkin/numpy,endolith/numpy,ahaldane/numpy,endolith/numpy,simongibbons/numpy,mhvk/numpy,ssanderson/numpy,anntzer/numpy,tynn/numpy,shoyer/numpy,gfyoung/numpy,ssanderson/numpy,ahaldane/numpy,pdebuyl/numpy,shoyer/numpy,MSeifert04/numpy,mhvk/numpy,shoyer/numpy,mattip/numpy,MSeifert04/numpy,behzadnouri/numpy,madphysicist/numpy,bertrand-l/numpy,tynn/numpy,jakirkham/numpy,grlee77/numpy,grlee77/numpy,tynn/numpy,jakirkham/numpy,pizzathief/numpy,grlee77/numpy,jorisvandenbossche/numpy,charris/numpy,numpy/numpy,solarjoe/numpy,shoyer/numpy,rgommers/numpy,chatcannon/numpy,pizzathief/numpy,behzadnouri/numpy,numpy/numpy,madphysicist/numpy,shoyer/numpy,bringingheavendown/numpy,jorisvandenbossche/numpy,simongibbons/numpy,rgommers/numpy,abalkin/numpy,abalkin/numpy,seberg/numpy,jakirkham/numpy,Eric89GXL/numpy,solarjoe/numpy,anntzer/numpy,bertrand-l/numpy,b-carter/numpy,ahaldane/numpy,MSeifert04/numpy,WarrenWeckesser/numpy,grlee77/numpy,madphysicist/numpy,charris/numpy,pizzathief/numpy,seberg/numpy,b-carter/numpy,mhvk/numpy,chatcannon/numpy,bringingheavendown/numpy,madphysicist/numpy,pizzathief/numpy,gfyoung/numpy,pdebuyl/numpy,seberg/numpy,pdebuyl/numpy,bringingheavendown/numpy,grlee77/numpy,seberg/numpy,jorisvandenbossche/numpy,WarrenWeckesser/numpy,mattip/numpy,jakirkham/numpy,MSeifert04/numpy,bertrand-l/numpy,mattip/numpy,mattip/numpy,endolith/numpy,simongibbons/numpy,pbrod/numpy,pbrod/numpy,solarjoe/numpy,charris/numpy,ssanderson/numpy,anntzer/numpy,gfyoung/numpy,MSeifert04/numpy,madphysicist/numpy,pbrod/numpy,WarrenWeckesser/numpy,Eric89GXL/numpy,pbrod/numpy,mhvk/numpy,charris/numpy,pdebuyl/numpy