occ command: add encryption version fix command

[mmattel]

What Needs to be Documented?

Upcoming new occ command
owncloud/core#35000 ([stable10] Backport of Add encryption version fix command)
Just for the record, a master forward port needs to be created

->setName('encryption:fixencryptedversion')
->setDescription('Fix the encrypted version if the encrypted file(s) are not downloadable.')

Where Does This Need To Be Documented?

occ command set

Why Should This Change Be Made? (Optional)

New core functionality
@sharidas pls add the rational behind that command

What Type Of Content Change Is This? (Optional)

• New Content Addition
• Old Content Deprecation
• Existing Content Simplification
• Bug Fix to Existing Content

Which Manual Does This Relate To? (Optional)

• Admin Manual
• Developer Manual
• User Manual
• Android
• iOS
• Branded Clients
• Desktop Client
• Other

Backporting to 10.1 or below based on feedback

@sharidas @PVince81 @settermjd

[pmaier1]

Will be part of Server 10.3. Needs to be documented soon therefore.