install: add instructions to update/uninstall DVC

[jorgeorpinel]

At least for the recommended install methods for each platform

First mentione in #695 (review)

[dashohoxha]

@jorgeorpinel Don't you think that the user should know how to use his commands (apt, yum, pip, etc.)? So, do we need to tell him how to update/upgrade a package?

I think that the same argument goes for telling users when and how to use a virtualenv. They should know when and how to use it, it should not be our concern. But this is a different topic.

[jorgeorpinel]

Yes, it's a good point @dashohoxha. But at least for pip, since upgrading can be different if you install from PyPi vs. if you install from local code, maybe we should include the commands in our docs.`

What do you think @shcheklein?

[jorgeorpinel]

On second thought I don't think my argument agains teaching other technologies really applies to installing and upgrading DVC, even if it's done with a 3rd party tool.

In fact maybe we should even include instructions to uninstall DVC as well somewhere. (Other similar tools offer this kind of information, probably because users look for it e.g https://devcenter.heroku.com/articles/heroku-cli#uninstalling-the-heroku-cli.)

Also, what should be the right term be: "update" or "upgrade"? 😋

[algomaster99]

@jorgeorpinel oh-my-zsh also does this. I think we should also have a command like uninstall_dvc which removes dvc installed from source or binary. Otherwise, there will be many separate instructions to uninstall it. If you think this is valid, please make it a separate issue.

[jorgeorpinel]

Not a bad idea. Opened treeverse/dvc/issues/2637 in parallel.

The question is should we provide instructions in the docs for now?

[shcheklein]

@jorgeorpinel nice, but not a top priority I would say. Uninstall can be really useful in some case (Mac OS package for example).