docs: Prepare for new sub tree

See #11925

docs/content/en/commands/hugo_new_theme.md

@@ -1,47 +0,0 @@
----
-title: "hugo new theme"
-slug: hugo_new_theme
-url: /commands/hugo_new_theme/
----
-## hugo new theme
-
-Create a new theme (skeleton)
-
-### Synopsis
-
-Create a new theme (skeleton) called [name] in ./themes.
-New theme is a skeleton. Please add content to the touched files. Add your
-name to the copyright line in the license and adjust the theme.toml file
-according to your needs.
-
-```
-hugo new theme [name] [flags]
-```
-
-### Options
-
-```
-  -h, --help   help for theme
-```
-
-### Options inherited from parent commands
-
-```
-      --clock string               set the clock used by Hugo, e.g. --clock 2021-11-06T22:30:00.00+09:00
-      --config string              config file (default is hugo.yaml|json|toml)
-      --configDir string           config dir (default "config")
-      --debug                      debug output
-  -d, --destination string         filesystem path to write files to
-  -e, --environment string         build environment
-      --ignoreVendorPaths string   ignores any _vendor for module paths matching the given Glob pattern
-      --logLevel string            log level (debug|info|warn|error)
-      --quiet                      build in quiet mode
-  -s, --source string              filesystem path to read files relative from
-      --themesDir string           filesystem path to themes directory
-  -v, --verbose                    verbose output
-```
-
-### SEE ALSO
-
-* [hugo new](/commands/hugo_new/)	 - Create new content for your site
-