add SponsorBlock & JumpCutter

[vitonsky]

Please confirm this pull request meets the following requirements:

• [x] I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• [x] I am not the sole author or employee of a company who created either the topic I am modifying/adding or the collection entry I am modifying/adding.

Which change are you proposing?

• [x] Suggesting edits to an existing topic or collection
• [ ] Curating a new topic or collection
• [ ] Something that does not neatly fit into the binary options above

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Editing an existing topic or collection

I'm suggesting these edits to an existing topic or collection:

• [ ] Image (and my file is *.png, square, dimensions 288x288, size <= 75 kB)
• [x] Content (and my changes are in index.md)

The Sponsor block and Jump cutter save me a lot of time.

Sponsor block let me skip ads and "integrations" segments embedded in video. According to their stats, i've save 11 days of live for users of Sponsor block:

 You've saved people from 7,409 segments
( 11d 17h 25.2 minutes of their lives )

You've skipped 2,596 segments ( 2d 9h 16.9 minutes ) 

Jump cutter does not have stats, but i think i saved a lot of time on jumps a video fragments with quiet.

So this both browser extension literally save my time. I want to invest couple minutes to add them into public list to share with other people.

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