Added documentation for tensor product and tensor contraction
Added documentation for tensor product and tensor contraction

lindsayad/sympy,jaimahajan1997/sympy,Curious72/sympy,kaushik94/sympy,yashsharan/sympy,rahuldan/sympy,ChristinaZografou/sympy,hargup/sympy,skidzo/sympy,souravsingh/sympy,postvakje/sympy,mafiya69/sympy,lindsayad/sympy,sampadsaha5/sympy,Titan-C/sympy,drufat/sympy,aktech/sympy,souravsingh/sympy,drufat/sympy,Curious72/sympy,mafiya69/sympy,yashsharan/sympy,chaffra/sympy,hargup/sympy,Titan-C/sympy,kaushik94/sympy,madan96/sympy,aktech/sympy,ChristinaZografou/sympy,jaimahajan1997/sympy,lindsayad/sympy,rahuldan/sympy,yashsharan/sympy,ChristinaZografou/sympy,jerli/sympy,jerli/sympy,postvakje/sympy,jerli/sympy,madan96/sympy,aktech/sympy,drufat/sympy,sampadsaha5/sympy,skidzo/sympy,souravsingh/sympy,Titan-C/sympy,Curious72/sympy,kaushik94/sympy,postvakje/sympy,jaimahajan1997/sympy,sampadsaha5/sympy,hargup/sympy,skidzo/sympy,mafiya69/sympy,madan96/sympy,rahuldan/sympy,chaffra/sympy,chaffra/sympy