Add iOSImageGenerator by @mizadi

[mizadi]

Added iOSImageGenerator under the photography category. Includes screenshot link and project metadata.

Add a project

1. Project URL:
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

Archive a project

1. Project URL:
2. Add archive tag

[dkhamsing]

There needs to be some changes but I'll do it

Thank you