Add guide about how to migrate from Redis

[nastena1606]

New topic page 'migration' about how to upgrade from Redis 7.2.5 for standalone and cluster.

[stockholmux]

Very good documents. I have mostly small changes for consistency and clarity.

Two other changes that are hard to remark in the review:

1. You need to fix your DCO issues. I always find this link to be helpful on fixing the DCO issues.
2. looks like you checked your pycache, that will need to be removed.

[zuiderkwast]

Great document. I didn't review it completely. I just noticed some things I wanted to comment on. Feel free to ignore the comments though.

[zuiderkwast]

"multi-threading" and "I/O threading" is the same thing.

If you want to mention three things, can we mention improved memory efficiency instead?

Regarding memory efficiency, I'm thinking about two things, perhaps too complex to mention here but just FYI:

1. the one-dict-per-slot in cluster mode (which also redis has, and had merged before we forked, but it's not included in any of the open source redis releases)
2. embedded key in dict entry

[stockholmux]

Some small rendering issues but otherwise LGTM.

[stockholmux]

You should drop the triple-backtick fencing when nesting code blocks in two level deep lists.

As written, the site renders like this

But because you can indents are also interpreted as code blocks the it still works. When I remove 54 and 59 it looks like this rendered on-site:

(You'll also need to remove this for the other alphabetical code blocks.)

[zuiderkwast]

This was surprising. There's something odd about the indentation here but I believe it should be possible to use triple backticks inside list items too.

If I read https://spec.commonmark.org/0.31.2/#list-items correctly, I believe you should indent the body of list item 2. Make aligned under "M" in "Make" and align the body of a. Connect under the "C" in "Connect", rather than adding 4 spaces for each level.

Example:

2. Make a backup of your Redis instance. 

   a. Connect to Redis and check the number of keys:

      ```
      code block
      ```

or, if you want four spaces indentation per level, you can add an extra space between "2." and "Make" and between "a." and "Connect".

2.  Make a backup of your Redis instance. 

    a.  Connect to Redis and check the number of keys:

        ```
        code block
        ```

[nastena1606]

I have tried to fix the indentation. When I build it locally it looks good for me but I cannot figure out how it renders on the website unfortunately.

[zuiderkwast]

This looks good to me in general. I don't have time to do a full review, sorry.