Update content.md to reflect Liquibase 5.0 changes

[jandroav]

This pull request updates the liquibase/content.md documentation to highlight major changes introduced in Liquibase 5.0. The most important updates clarify the separation between the open source and commercial editions, and document breaking changes regarding database drivers and extensions.

Liquibase 5.0 product separation and usage:

• Added a section describing the distinction between the OSS edition (liquibase/liquibase) under the Functional Source License (FSL) and the commercial Secure edition (liquibase/liquibase-secure), including guidance for users with a license key.

Breaking changes to driver and extension management:

• Documented that database drivers and extensions are no longer included by default in the OSS edition and official Docker image, requiring explicit installation via the Liquibase Package Manager (LPM) or manual mounting.
• Provided instructions and Dockerfile examples for adding database drivers using LPM, and clarified continued support for MySQL driver installation via the INSTALL_MYSQL=true environment variable.

Reference to release announcement:

• Included a link to the official Liquibase 5.0 release announcement for further details.

[jandroav]

I fixed the markdown lint issue, but amending the commit to a single commit doesn’t re-trigger the CI job.

[tianon]

Thanks for getting this started!

I think this needs to be more explicit about the fact that 5.0 will be the last version supported here and that users should very actively transition over to liquibase/liquibase{,-secure} images instead. We support a deprecated.md file that's intended for this exact purpose that I think we need to make explicit use of here, especially as it will render above everything else.

Here's a proposed start to something like that (consistent with how we've done this in the past): 72010b9

That necessarily implies some changes to the contents of this PR too 🙈
(if only we'd caught this sooner and stopped 5.x from entering this program entirely so the breaking changes don't need to be documented here too 😅 😞)

One thing we could consider is moving latest back to 4.x here (or even dropping the latest tag entirely).

Then we could also add something like "for details of breaking changes in 5.x, see X" if you've got some upstream documentation somewhere that explains all this nicely? (that would shrink the needed documentation here for 5.0 that then needs to be maintained over time)

[jandroav]

Thanks @tianon, I added your suggestions. I would like @jnewton03 chime in

[jnewton03]

If it is okay we would like to keep the current tag as the last release of the official image. We will be updating our docs and readmes to point to liquibase/liquibase for community and direct users that direction for any future releases. We appreciate all of your help @tianon !

[tianon]

Looks good to me ❤️

Just the markdownfmt from the CI -- I'm happy to help apply that if that would be helpful. 👍