added release notes for 2.10 and 2.11

[smahati]

Description

Changes proposed in this pull request:

• added release notes
• minor grammatical changes in the text

Related issue(s)

Resolves #3692

[smahati]

@JohannesDoberer I see another release should I add notes for it as well?

[JohannesDoberer]

@smahati, up to you. Either create a new blog post issue or add it to this pr.