docs. Regen CLI docs

Closes #9363

docs/content/en/commands/hugo_server.md

@@ -58,6 +58,7 @@ hugo server [flags]
       --noChmod                don't sync permission mode of files
       --noHTTPCache            prevent HTTP caching
       --noTimes                don't sync modification time of files
+      --panicOnWarning         panic on first WARNING log
       --path-warnings          print warnings on duplicate target paths etc.
       --poll string            set this to a poll interval, e.g --poll 700ms, to use a poll based approach to watch for file system changes
   -p, --port int               port on which the server will listen (default 1313)