More docs and 'variables' option.
More docs and 'variables' option.

kaushik94/sympy,kaushik94/sympy,chaffra/sympy,yashsharan/sympy,skidzo/sympy,jaimahajan1997/sympy,chaffra/sympy,yashsharan/sympy,jaimahajan1997/sympy,jaimahajan1997/sympy,madan96/sympy,madan96/sympy,kaushik94/sympy,skidzo/sympy,madan96/sympy,skidzo/sympy,chaffra/sympy,yashsharan/sympy