Restructure releases section

[p7nov]

Resolves #4055

Deployment: https://docs.d.tarantool.io/en/doc/gh-4055-releases-update/release/

Changes:

• Add the 3.0.1 version to the releases table and 3.0 What's new page.
• Add EOS date for 2.8: 31.12.2024 to the releases table
• Drop the release calendar page:
  • Move the info about supported versions to the main Releases page.
  • Move the info about EOL versions to the EOL versions page.
• Reformat table with supported releases info on the Releases page for better readability.
• Draw new release calendar diagram based on corporate visual style for Gantt charts.
• Move EE SDK changelog into the Releases section.
• Hide legacy release policy and list of major features of EOL versions into the EOL section.
• Add an admonition that Major features table is no longer maintained.
• Drop release policies overview page and move the current (aka new) policy page directly inside the Releases section.

Need redirects: https://github.com/tarantool/tarantool.io/pull/1518

release/calendar/ > release/
release/policy_index/ > release/policy/

[andreyaksenov]

Cool, some minor comments from me:

[andreyaksenov]

I'd remove bold formatting from regular table rows - looks like header rows sneaked into the middle of the table. IMO, additional marking of such rows in bold is excessive and adds some visual clutter.

And I'd also add header formatting to the first row (Series, First release date, ...).

[andreyaksenov]

Lets make this toctree :hidden: to avoid duplication.