Add anchors to show/hide sections in install page

[abbycross]

EDIT: Adding custom anchor tags to the show/hide sections in the "Qiskit versioning" section.

Once this is merged, direct links to the show-hide sections will be:

https://docs.quantum.ibm.com/start/install#release-schedule
https://docs.quantum.ibm.com/start/install#upgrade-strategy
https://docs.quantum.ibm.com/start/install#pre-releases
https://docs.quantum.ibm.com/start/install#post-releases

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(Original proposal below, for historical purposes; we are no longer separating out the versioning section to a new page.)
In discussions with @mtreinish, the proposal is to separate out the versioning section (currently at the end of the start/install page) into a new page, for the following reasons:

• it really isn't directly install-related
• it allows us to remove the show/hide features for that content, which makes it easier to link to and find

We may also want to remove the show/hide features for the OS support tiers, but leave them in the current install page, since they are install-related.

Topics to discuss:

• What to put in Next steps section? Currently using the same as what is on the Install pg as a placeholder.
• Title at the moment is just Qiskit versioning (since that's the only thing in the new page); are we good with this?
• I put the new page after the "Advanced setup" section in the toc. Should it be elsewhere?

cc: @mtreinish @Eric-Arellano

[abbycross]

Ignore my first commit -- it's no longer the direction we're going in!!

[abbycross]

Update: @javabster suggested trying

<summary id="anchor-name">Description words</summary>

within the <details> tags, and this works much better than <span>. In theory we can bring the show/hide sections back and keep everything on the same page -- however, we still do not have a way for the reader to copy an anchor's link (no little chain icon shows up). That alone may be reason enough to split out the content into a separate page; otherwise the reader would have to look at the code to discover the anchor tag.

One option is to include a header within the show/hide content itself, which would show the chain icon, AND this means the header would show up on the right nav (if it's h2 or h3), but then we would have a duplicated line situation like this:

Another option is to create the header right within the summary tags, which would work great if the chain icon wasn't superimposed with the caret to click on!!

Thoughts or reasonable workarounds appreciated!... I have scoured the internet but perhaps am not using the right search terms...

[abbycross]

Had an offline conversation with @javabster and we determined that the best way to move forward is to return to the original formatting of this content and create custom anchor links for the show/hide sections. In the future we hope to have a better component for the show-hide sections so that we can more flexibly link to them.

[abbycross]

One last comment: while this functionality works, the links may appear only to jump to the Qiskit versioning section, because the show/hide section is so close to the end of the page. 🤷