Tax Exemption

I already filed my taxes, but I was just reading through a pamphlet they gave me at the Tax Office and read under “Scope of Exemption”: The following categories of income can be exempted by submitting the necessary documents. (2)Salaries of teachers and employees of nurseries, kindergartens, public promary and junior high schools, and private primary and junior high schools.

SO…does this mean that if I work at a kindergarten, I do not have to pay taxes? What would those NECESSARY DOCUMENTS mean?