doc: Upgrade from an old Gitea (#16918)

doc: Upgrade from an old Gitea (#16918)

* doc: Upgrade from an old Gitea

* update backup steps

* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
* update backup tips

* update table header

* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: silverwind <me@silverwind.io>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: silverwind <me@silverwind.io>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: techknowlogick <matti@mdranta.net>
* Update docs/content/doc/upgrade/from-gitea.en-us.md

Co-authored-by: techknowlogick <matti@mdranta.net>
* Update from-gitea.en-us.md

* Update from-gitea.en-us.md

* Update from-gitea.en-us.md

* Update from-gitea.en-us.md

* Update from-gitea.en-us.md

* Update from-gitea.en-us.md

* Update from-gitea.en-us.md

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: techknowlogick <matti@mdranta.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>