docs: add 5.1 migration guide

[dhrudevalia]

Issue

From 5.0.x -> 5.1 many configuration keys have been updated and changed. To make the upgrade process easier the 5.0.6 connector prints an automatically migrated configuration to the log

Docs update

• Add migration guide for:
  • Confluent Cloud
  • Confluent Platform

[ali-ince]

I think it would be nice to have a top-level Migration section, under which we have two separate pages, one for Confluent Platform and another for Confluent Cloud. We can place the Migration section just before Reference?

[ali-ince]

LGTM

[ali-ince]

@nvitucci would you please take a look at this one?

[nvitucci]

@ali-ince @dhrudevalia I have a few questions first:

• Do you have any specific reasons to consider this a "migration" rather than an "upgrade"? We tend to reserve the term "migration" for cases where there are breaking changes or that require changes in the data. Also, the link to Confluent takes to an "Upgrade" page.
• If this is actually a "migration" and we expect non-breaking "upgrades" in the future, a better name for the section may be "Upgrades and migrations".
• Are we already expecting future versions that will require upgrade/migration instructions? I am with @dhrudevalia anyway regarding having a fixed version number in the context of an upgrade/migration, and I would go one step further and have it as a nav item (something like "5.0 -> 5.1" instead of the generic "Overview"), with the idea that future upgrade/migrations will also have their own pages (for example, "5.1 to 5.2" or "5.x to 6.0"). There are good examples in the Neo4j Update and migration guide.
• Since the overview refers to the "What's new" page, I think it makes sense to have a specific 5.1 header there to refer to. This would be useful for future similar pages.

[ali-ince]

Hey @nvitucci,

• we have breaking configuration changes from 5.0 to 5.1, and can not do an in-place upgrade. I think this qualifies it to be mentioned as migration?
• We'll do our best to keep away from breaking changes for the upcoming releases, but still happy to mention it as Upgrades and migrations as the section title.
• I'm happy with your suggestion of 5.0 -> 5.1 instead of overview.
• Sure.

@dhrudevalia do you mind making the changes @nvitucci suggested above?

[nvitucci]

Thank you, @ali-ince. So:

• It's fine to use "migration" then.
• That's ok, what I wanted to understand is if we're planning to make any other releases that will need any instructions to add to the list, which will then be classified as migrations (like this one) or upgrades (non-breaking changes).
• 5.0 to 5.1 might be better.

I'll add a couple more specific suggestions to each page as well, but these were the main decision points. Thanks!

[nvitucci]

I've left several (mostly minor) comments to improve readability.

[nvitucci]

Few more minor comments. Other than that, it's good for me.

[neo-technology-commit-status-publisher]

Thanks for the documentation updates.

The preview documentation has now been torn down - reopening this PR will republish it.