2.11 calendar and release information update

[AArdeev]

Product: Tarantool
Since: 2.11
Root document: https://www.tarantool.io/en/doc/2.11/release/
SME: @ hackallcode

Details

To be done after #5281

• Pages https://www.tarantool.io/en/doc/2.11/release/calendar/.
  Limit calendar in "2.11" with 2026.
Add references from "2.11" to "latest" and.
• Page https://www.tarantool.io/en/doc/2.11/release/.
  In "2.11", all releases are EOL, therefore the EOL Versions section seems excessive. The section must be renamed to Tarantool Versions and a warning box must be added. In the warning box there must be info about all 1.x and 2.x versions being EOL, and a link to Latest doc.
• Page https://www.tarantool.io/en/doc/2.11/release/.
  The Releases page is misleading now and has to be checked with SME and rewritten. Remove anything older than 3.0.0 (incl) from the table and delete the note before the table.
• Page https://www.tarantool.io/en/doc/2.11/release/policy_index/.
  Both release policies must be rewritten in timeless style and be renamed as "Policies until 2.9" and "Policies after 2.10"