Reorder sampling docs

[Asmatzaile]

This PR restructures the samplers and sampling pages of the documentation so that groupings make more sense, follow up to PR #269.

SAMPLERS PAGE

• amp and gain were moved from samplers>basic sample manipulation to audio effects.
• What was left in samplers were sample speed related effects (accelerate, speed, unit, timescale, and timescalewin). I thus renamed samplers to sample_speed

SAMPLING PAGE

• I moved sampling>signal sampling (segment, discretise, sig) to oscillators.
• I moved loopAt to the previously renamed sample_speed page
• What was left in sampling were functions for sample slicing, so I renamed the page accordingly.

This PR also updates sidebars.js, which should make the new page of the previous PR appear.

[cleary]

This build check is failing, does it depend on your previous PR (#269)?

[Asmatzaile]

This build check is failing, does it depend on your previous PR (#269)?

seems like I had to update sidebars.js (:

[Asmatzaile]

Hi @cleary! Is this PR going to be merged or should I close it?

[cleary]

Just leave it open for the moment - I was attempting to gain some clarity on the status of a bigger rewrite and how we handle changes happening in the meantime. I need to review when I have a bit of spare time

[cleary]

Hi,
Thanks for all your work on this, and (massive) apologies that it's taken me so long to review.

The ideas all look good, I think you've moved things appropriately - one minor/optional change request:
In sample_trimming.md: make the "Event-relative" and "Relative to the sample length" headings consistent

The other thing is it's no longer merging cleanly - are you able to take a look at getting the master branch updates in for a clean merge and I will accept