Enable categories's feature.
Enable categories's feature(2).
Enable categories's feature(3).
Enable category description on the index page of listing quizzes.
Merge pull request #136 from not001praween001/about-category

Enable categories's feature.
Merge pull request #137 from not001praween001/about-category

Enable categories's feature(3).
Merge pull request #138 from not001praween001/about-category-2

Enable category description on the index page of listing quizzes.