[5pt] Release notes for Tarantool releases in 2020-04

[NickVolynkin]

Feature name

Fill in whatever you know at the moment.

Product: Tarantool
Since: 2.8.1, 2.7.2, 2.6.3
Root document: https://www.tarantool.io/en/doc/latest/release/
SME: @kyukhin
Peer reviewer: @

Sources:

https://github.com/tarantool/tarantool/blob/master/changelogs/2.8.1.md
https://github.com/tarantool/tarantool/blob/2.7/changelogs/2.7.2.md
https://github.com/tarantool/tarantool/blob/2.6/changelogs/2.6.3.md
https://github.com/tarantool/tarantool/blob/1.10/changelogs/1.10.10.md

Definition of done

• add new pages as children of https://www.tarantool.io/en/doc/latest/release/
• add links to them to the table at https://www.tarantool.io/en/doc/latest/release/
• rephrase the notes as in 2.7.1, check and fix English
• give links to documentation, where possible