docs: release notes for v2.27 (#28121)
docs: release notes for v2.27 (#28121)

* docs: release notes for v2.27 (WIP)

* Add writeup of SSR in development

* add lazy dev bundling

* Update index.md

* Add review sugestions

* added notes, restructured a bit

* Add mention of GATSBY_EXPERIMENTAL_FAST_DEV

* lint, cleanup

* cleanup

* Update docs/reference/release-notes/v2.27/index.md

Co-authored-by: Matt Kane <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@gatsbyjs.com>

* Update docs/reference/release-notes/v2.27/index.md

Co-authored-by: Lennart <074ba1c0efc36927866875b17be4fa06eb80e472@gmail.com>

* Update docs/reference/release-notes/v2.27/index.md

Co-authored-by: Lennart <074ba1c0efc36927866875b17be4fa06eb80e472@gmail.com>

* Update docs/reference/release-notes/v2.27/index.md

Co-authored-by: Lennart <074ba1c0efc36927866875b17be4fa06eb80e472@gmail.com>

* Update docs/reference/release-notes/v2.27/index.md

Co-authored-by: Lennart <074ba1c0efc36927866875b17be4fa06eb80e472@gmail.com>

* Update docs/reference/release-notes/v2.27/index.md

Co-authored-by: Lennart <074ba1c0efc36927866875b17be4fa06eb80e472@gmail.com>

* fix headers

Co-authored-by: Kyle Mathews <7bd94dfba4631668b5e30ca2e1b9b5e24b0f4d74@gmail.com>
Co-authored-by: Matt Kane <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@gatsbyjs.com>
Co-authored-by: Lennart <074ba1c0efc36927866875b17be4fa06eb80e472@gmail.com>
gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby