5 documentation about using timer

[baobuibk]

@TransistorTun em phải merge với cái remote master mới nhất trước Theo tutorial này nhé

https://stackoverflow.com/questions/47029731/git-get-latest-changes-before-pushing-a-branch

2. Go to master branch with: git checkout master
3. Update your local master with: git pull origin master
4. Resolve conflicts (if applicable)
5. Go back to features with: git checkout features
6. Merge master branch over features with: git merge master
7. Push changes with: git push origin features

Lưu ý: feature là cái branch của em (5-documentation about timer)