Add Off-Day

[csprasad]

Add a project

1. Project URL: https://github.com/zizicici/Off-Day
2. Update contents.json instead of README
3. One project per pull request
4. Screenshot included
5. Avoid iOS or open-source in description as it is assumed
6. Use this commit title format if applicable: Add app-name by @github-username
7. Use approved format for your entry

[dkhamsing]

Will clean this up, thx for the contribution