Fix ERR_FILE_NOT_FOUND when running npm test

[Smankusors]

Proposed changes

When running npm test, there's a warning shown below when testing Card and Sidenav plugin

log: Failed to load resource: net::ERR_FILE_NOT_FOUND
log: Failed to load resource: the server responded with a status of 403 (Forbidden)

This is happen when we merged #78, where the "images" folder moved to "docs" folder. This PR fixes the img src to the updated one. There's also one image on the card component that become missing (403 forbidden), so I replaced it with sample-1.jpg.

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to change).

Checklist:

• I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.