Publish 2.10.3 changelog

[p7nov]

Publish changelog/release notes for Tarantool 2.10.3 in docs

Source

https://github.com/tarantool/tarantool/blob/2.10/changelogs/2.10.3.md

Definition of done

• Create a new page and add the 2.10.3 changelog
• Update the Release Notes page
• Check the Major features page
• Update the release calendar page
• Add cross-links if needed
• Add links to GH issues