Documentation: Update ReadMe with latest features and updates

[fxstein]

Update README.md to reflect the recent changes from:

• Feature: Test Storage Hierarchy before Operations #12 Feature: Test Storage Hierarchy before Operations
• Feature: Import from Archive #14 Feature: Import from Archive
• Feature: exiftool error handling #19 Feature: exiftool error handling

In addition, correct the 360 file handling description that states incorrectly that 360 files become mp4 files after processing. This was an earlier attempt that turned out to be an unworkable solution.