Clarify "subtitle delay" dialogue

[Rotekoppen]

This issue respects the following points:

• This issue is not already reported on GitHub (I've searched it).
• I agree to follow Jellyfin's Code of Conduct.
• This report addresses only a single issue; If you encounter multiple issues, kindly create separate reports for each one.

Describe the bug

The current slider does not intuitively tell what you should do if subtitles are too late or too early.

Reproduction Steps

Not applicable

Expected/Actual behaviour

The dialogue should provide some way to tell how you are changing the subtitles, the arbituary positive or negative number gives the user no idea what it actually means nor how to use it.

A solution could be text saying "Increase the delay if subtitles are too early, decrease if late"

Logs

No response

Server version

10.11.8

Web version

10.11.8

Build version

10.11.8

Platform

Any (found on web and tizen)

Browser

any

Additional information

Really sorry if this is the wrong place to post usability/accessibility issues >.<