That is probably worth what you pay for it. I'd be happy to let an Indian lawyer review documents under Indian law but for a situation in the US or in Europe I'd use a local lawyer specializing in the problem domain (in this case labour law).

'Generic legal language' is not your problem, specific legal language applicable to this specific case is the problem and if $20 is the differentiating factor then you might as well quit the job or sign the contract anyway.