Improve the docs for the preview() method
Improve the docs for the preview() method

Signed-off-by: Ondrej Certik <b816faa87b7d35274d2e545c5be11ed4376f3ccf@certik.cz>
Signed-off-by: Jan Minar <69eb0ad528afbcd1e66576da6874b36fe46acbb8@googlemail.com>

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