Update en-us and fr-fr versions of the "Upgrade from Gogs" doc (#4618)
* Update "Upgrade from Gogs" en-us doc
- Move "Change gogs specific information" FROM/TO steps up
to just beneath matching section header, adjust indention
and explicitly specify syntax of code sample to provide
highlighting
- Adjust header levels to match what appears to be the
intended level, remove trailing decoration (see below)
- Move "Upgrading to most recent ..." section down, remove
decoration (section header formatting likely covers this
well enough already)
refs go-gitea/gitea#4286, go-gitea/gitea#3558
* Update "Upgrade from Gogs" fr-fr doc
- Adjust indention and explicitly specify syntax of code
sample to provide highlighting
- Adjust header levels to match what appears to be the
intended level, remove trailing decoration since
section header formatting likely covers this
well enough already
refs go-gitea/gitea#4286, go-gitea/gitea#3558
ZHOU Cheng
kolaente
Johan Van de Wauw
Aidan Fitzgerald
Shikiryu
Deoren Moor
Victor Polevoy
Michael Lustfield
techknowlogick