https://github.com/spree/spree/tree/master/guides/content/release_notes
https://github.com/spree/spree/blob/master/guides/content/release_notes/3_1_0.md
https://github.com/spree/spree/blob/master/guides/content/release_notes/3_0_0.md
https://github.com/spree/spree/blob/master/guides/content/release_notes/2_4_0.md