Move and fix up lifecycle start/stop/check docs

[kilfoyle]

As discussed as part of Edu's ILM docs review, this PR:

• Removes the Start and stop ILM page
• Merges that content into Troubleshoot index and snapshot lifecycle management
• Adds steps into that latter page for stopping and checking the status of snapshot lifecycle management (SLM) (I've tested the new steps to make sure they're correct)
• Adds some context around why we would do these things.

Please see the updated version: Troubleshoot index and snapshot lifecycle management

Rel: #190

[github-actions]

🔍 Preview links for changed docs

• manage-data/lifecycle/index-lifecycle-management.md
• manage-data/lifecycle/index-lifecycle-management/start-stop-index-lifecycle-management.md
• troubleshoot/elasticsearch/start-ilm.md

[yetanothertw]

I've left a few comments for your consideration. Let me know what you think.

[yetanothertw]

I've left some minor formatting comments and something odd is going on with the mini TOC here

[yetanothertw]

Not sure what is causing this (maybe it's the snippet?), but there's some funkiness going on with the mini-toc on the right (the order of the headings does not reflect the actual page):

[kilfoyle]

Thanks for catching that @yetanothertw ! I can't figure out why it's not working, but reversing the order with the SLM section first allows the right-side nav to display properly. So now it looks like this:

[kilfoyle]

Hmm. The preview version doesn't seem to show the above yet.

[kilfoyle]

In my local preview build the right-side navigation displays nicely, but in the PR preview build the navigation seems to be in the wrong order. I've opened an issue for this: elastic/docs-builder#1880

[yetanothertw]

Still looks off, even with the inverted order:

I think you might have to try the workaround that Shaina suggested, hopefully that'll do it. 🤞

[shainaraskas]

approved in theory. will say that the only workaround I know of for this annoying heading issue is to break the snippet up and add the headings to the targets.

[kilfoyle]

Thanks. I split up the snippets file as suggested. Not ideal but at least our nav looks less wonky. :-)