Atto media plugin help needs improving

There is no documentation present in the Moodle Docs for the Captions and Audio Description functionality that was introduced in Moodle 3.2. The only documentation that could be found was a brief announcement on the Moodle Announcements page and a single bullet in the Moodle 3.2 release notes. The help information available in the Insert Media dialog was not useful when issues were encountered while attempting to upload captions and descriptions. Errors also did not provide  useful information, such as supported file types, sizes, etc.    

Items that should be included in the Help information provided in the Insert Media dialog include:

• Supported file types for captions and audio descriptions
• Supported file sizes (this was an issue testing on accessibility.moodle.net)

Items that should be included in the documentation include:

• Conversion solutions as many tools do not produce .VTT
• Instructions and screenshots for uploading captions/descriptions
• Known Issues
• Details on DCMP Compliance related to timing, positioning, etc.

 Replication Instructions:

1. Review Moodle Docs for information on the Moodle 3.2 Media Player and attempt to find documentation addressing the items above.
2. Review the Help information provided in the Insert Media dialog and attempt to find information on the items listed above.