DOC: Integrate: Add positive infinity specifier in `dblquad` example.
DOC: Integrate: Add positive infinity specifier in `dblquad` example.

mdhaber/scipy,rgommers/scipy,Stefan-Endres/scipy,ilayn/scipy,scipy/scipy,andyfaff/scipy,perimosocordiae/scipy,anntzer/scipy,mdhaber/scipy,endolith/scipy,perimosocordiae/scipy,endolith/scipy,endolith/scipy,Stefan-Endres/scipy,anntzer/scipy,perimosocordiae/scipy,rgommers/scipy,anntzer/scipy,scipy/scipy,Stefan-Endres/scipy,scipy/scipy,anntzer/scipy,perimosocordiae/scipy,ilayn/scipy,perimosocordiae/scipy,andyfaff/scipy,perimosocordiae/scipy,endolith/scipy,WarrenWeckesser/scipy,endolith/scipy,Stefan-Endres/scipy,andyfaff/scipy,anntzer/scipy,Stefan-Endres/scipy,WarrenWeckesser/scipy,anntzer/scipy,rgommers/scipy,mdhaber/scipy,endolith/scipy,ilayn/scipy,WarrenWeckesser/scipy,mdhaber/scipy,andyfaff/scipy,rgommers/scipy,ilayn/scipy,andyfaff/scipy,WarrenWeckesser/scipy,scipy/scipy,ilayn/scipy,WarrenWeckesser/scipy,scipy/scipy,andyfaff/scipy,WarrenWeckesser/scipy,ilayn/scipy,mdhaber/scipy,rgommers/scipy,Stefan-Endres/scipy,scipy/scipy,mdhaber/scipy