added details about all inv methods
added details about all inv methods

Also fixed indentation issue.
aktech/sympy,skidzo/sympy,drufat/sympy,postvakje/sympy,aktech/sympy,jaimahajan1997/sympy,drufat/sympy,souravsingh/sympy,sampadsaha5/sympy,skidzo/sympy,jaimahajan1997/sympy,chaffra/sympy,souravsingh/sympy,jaimahajan1997/sympy,kaushik94/sympy,drufat/sympy,madan96/sympy,skidzo/sympy,yashsharan/sympy,kaushik94/sympy,aktech/sympy,yashsharan/sympy,yashsharan/sympy,postvakje/sympy,sampadsaha5/sympy,postvakje/sympy,chaffra/sympy,sampadsaha5/sympy,souravsingh/sympy,kaushik94/sympy,chaffra/sympy,madan96/sympy,madan96/sympy