combinatorics/permutations: Fixed various docstrings and doctests.
combinatorics/permutations: Fixed various docstrings and doctests.

Signed-off-by: Saptarshi Mandal <13ec3c7bab52575f3a0cda6406c76269cc13b041@gmail.com>

souravsingh/sympy,souravsingh/sympy,sahmed95/sympy,grevutiu-gabriel/sympy,chaffra/sympy,AkademieOlympia/sympy,pandeyadarsh/sympy,Curious72/sympy,chaffra/sympy,vipulroxx/sympy,drufat/sympy,Arafatk/sympy,skidzo/sympy,moble/sympy,shipci/sympy,dqnykamp/sympy,skidzo/sympy,shikil/sympy,ahhda/sympy,Arafatk/sympy,grevutiu-gabriel/sympy,jamesblunt/sympy,sunny94/temp,drufat/sympy,saurabhjn76/sympy,Titan-C/sympy,abhiii5459/sympy,souravsingh/sympy,rahuldan/sympy,atreyv/sympy,Mitchkoens/sympy,grevutiu-gabriel/sympy,wanglongqi/sympy,kevalds51/sympy,Arafatk/sympy,dqnykamp/sympy,jaimahajan1997/sympy,Designist/sympy,Sumith1896/sympy,MridulS/sympy,hargup/sympy,sunny94/temp,meghana1995/sympy,kevalds51/sympy,Gadal/sympy,kaichogami/sympy,skirpichev/omg,wyom/sympy,liangjiaxing/sympy,yukoba/sympy,beni55/sympy,sahilshekhawat/sympy,AkademieOlympia/sympy,rahuldan/sympy,toolforger/sympy,pandeyadarsh/sympy,madan96/sympy,shikil/sympy,yashsharan/sympy,Vishluck/sympy,Designist/sympy,ahhda/sympy,pandeyadarsh/sympy,aktech/sympy,jerli/sympy,Designist/sympy,bukzor/sympy,abloomston/sympy,asm666/sympy,bukzor/sympy,jaimahajan1997/sympy,postvakje/sympy,shikil/sympy,aktech/sympy,asm666/sympy,asm666/sympy,meghana1995/sympy,jerli/sympy,postvakje/sympy,chaffra/sympy,maniteja123/sympy,madan96/sympy,yukoba/sympy,yukoba/sympy,Shaswat27/sympy,Davidjohnwilson/sympy,saurabhjn76/sympy,emon10005/sympy,jbbskinny/sympy,debugger22/sympy,kaichogami/sympy,toolforger/sympy,Davidjohnwilson/sympy,vipulroxx/sympy,sampadsaha5/sympy,mafiya69/sympy,lindsayad/sympy,hrashk/sympy,kumarkrishna/sympy,jerli/sympy,Gadal/sympy,abhiii5459/sympy,mcdaniel67/sympy,ga7g08/sympy,bukzor/sympy,kmacinnis/sympy,yashsharan/sympy,sampadsaha5/sympy,Sumith1896/sympy,Vishluck/sympy,garvitr/sympy,ga7g08/sympy,wanglongqi/sympy,beni55/sympy,diofant/diofant,cccfran/sympy,sunny94/temp,abloomston/sympy,farhaanbukhsh/sympy,oliverlee/sympy,sahmed95/sympy,kmacinnis/sympy,sahilshekhawat/sympy,Gadal/sympy,kevalds51/sympy,kmacinnis/sympy,amitjamadagni/sympy,Titan-C/sympy,kaichogami/sympy,sahilshekhawat/sympy,ga7g08/sympy,drufat/sympy,aktech/sympy,iamutkarshtiwari/sympy,liangjiaxing/sympy,Davidjohnwilson/sympy,farhaanbukhsh/sympy,Sumith1896/sympy,iamutkarshtiwari/sympy,AunShiLord/sympy,cccfran/sympy,MechCoder/sympy,Shaswat27/sympy,atsao72/sympy,MridulS/sympy,kumarkrishna/sympy,madan96/sympy,lidavidm/sympy,pbrady/sympy,lidavidm/sympy,Mitchkoens/sympy,cswiercz/sympy,liangjiaxing/sympy,atsao72/sympy,jamesblunt/sympy,garvitr/sympy,yashsharan/sympy,skidzo/sympy,moble/sympy,pbrady/sympy,meghana1995/sympy,debugger22/sympy,kumarkrishna/sympy,sampadsaha5/sympy,hargup/sympy,Shaswat27/sympy,rahuldan/sympy,AunShiLord/sympy,ChristinaZografou/sympy,wanglongqi/sympy,mcdaniel67/sympy,lidavidm/sympy,jbbskinny/sympy,Mitchkoens/sympy,MechCoder/sympy,srjoglekar246/sympy,hargup/sympy,pbrady/sympy,mafiya69/sympy,abloomston/sympy,amitjamadagni/sympy,lindsayad/sympy,saurabhjn76/sympy,Titan-C/sympy,toolforger/sympy,maniteja123/sympy,VaibhavAgarwalVA/sympy,wyom/sympy,Curious72/sympy,hrashk/sympy,AunShiLord/sympy,kaushik94/sympy,vipulroxx/sympy,maniteja123/sympy,jaimahajan1997/sympy,debugger22/sympy,AkademieOlympia/sympy,atsao72/sympy,kaushik94/sympy,beni55/sympy,flacjacket/sympy,cswiercz/sympy,emon10005/sympy,mafiya69/sympy,Vishluck/sympy,dqnykamp/sympy,oliverlee/sympy,wyom/sympy,MridulS/sympy,ChristinaZografou/sympy,garvitr/sympy,jamesblunt/sympy,shipci/sympy,MechCoder/sympy,abhiii5459/sympy,moble/sympy,shipci/sympy,postvakje/sympy,cswiercz/sympy,ahhda/sympy,VaibhavAgarwalVA/sympy,Curious72/sympy,farhaanbukhsh/sympy,mcdaniel67/sympy,atreyv/sympy,VaibhavAgarwalVA/sympy,atreyv/sympy,iamutkarshtiwari/sympy,ChristinaZografou/sympy,emon10005/sympy,oliverlee/sympy,kaushik94/sympy,hrashk/sympy,cccfran/sympy,sahmed95/sympy,jbbskinny/sympy,lindsayad/sympy