user-guide: merge/remove duplicate pages from new Installation subsection

[dashohoxha]

• Move installation page to the top level of the docs (currently it is under the user-guide).
• Remove https://dvc.org/doc/user-guide/plugins (which is now located under installation). See user-guide: reorganize installation page into this section #695 (review)
• Update https://dvc.org/doc/user-guide/development. See details in user-guide: duplicate dev version docs (with different methods) #700.
• Simplify https://dvc.org/doc/get-started/install and maybe merge it with the next section (https://dvc.org/doc/get-started/initialize). See user-guide: reorganize installation page into this section #695 (review)
• Find all links to the removed pages and redirect them to the new pages.

Depends on: #695
Related: #700 , #660

[jorgeorpinel]

Awesome. This would be worked on immediately after #695 is closed?

And can we include adding relevant Updating DVC notes here? (See #695 (review).) Or should I open a separate issue?

[shcheklein]

@jorgeorpinel I would keep it as a separate ticket. It's not a simple one :)

[jorgeorpinel]

OK, moved to #702

[jorgeorpinel]

Remove https://dvc.org/doc/user-guide/development...

I'm addressing this in 1774355 as part of the current PR #695.

[jorgeorpinel]

Update https://dvc.org/doc/user-guide/development. See details in #700.

This one part is not done right. See #701 (comment). It should be re-done by re-applying the changes in 1774355 which were reverted as explained in #695 (review).

[shcheklein]

@jorgeorpinel since the PR has been merged you need to create a new with these changes probably?

[dashohoxha]

It should be re-done by re-applying the changes

@jorgeorpinel The necessary changes have been applied correctly, please check it again. So, let's close this issue (an open another one if needed).

[jorgeorpinel]

Yes @shcheklein, a new PR is needed to fix this. I am happy to do this work myself again, but do we agree that undoing other people's work is confusing and unproductive? I could've missed this problem for example, and it would be totally lost.

In this particular case, I was asked to review that PR in #695 (comment), then I was asked for help on it in #695 (comment), and then when I contributed to the branch, my work was literally reverted. In fact this may be happening again in #732 (comment) right now...

[jorgeorpinel]

Done. This will be closed in 876034b.