Rename actions unit to `repo.actions` and add docs for it (#23733)

I neglected that the `NameKey` of `Unit` is not only for translation,
but also configuration. So it should be `repo.actions` to maintain
consistency.

## :warning: BREAKING :warning:

If users already use `actions.actions` in `DISABLED_REPO_UNITS` or
`DEFAULT_REPO_UNITS`, it will be treated as an invalid unit key.

custom/conf/app.example.ini

@@ -947,10 +947,10 @@ ROUTER = console
 ;USE_COMPAT_SSH_URI = false
 ;;
 ;; Close issues as long as a commit on any branch marks it as fixed
-;; Comma separated list of globally disabled repo units. Allowed values: repo.issues, repo.ext_issues, repo.pulls, repo.wiki, repo.ext_wiki, repo.projects, repo.packages
+;; Comma separated list of globally disabled repo units. Allowed values: repo.issues, repo.ext_issues, repo.pulls, repo.wiki, repo.ext_wiki, repo.projects, repo.packages, repo.actions.
 ;DISABLED_REPO_UNITS =
 ;;
-;; Comma separated list of default new repo units. Allowed values: repo.code, repo.releases, repo.issues, repo.pulls, repo.wiki, repo.projects, repo.packages.
+;; Comma separated list of default new repo units. Allowed values: repo.code, repo.releases, repo.issues, repo.pulls, repo.wiki, repo.projects, repo.packages, repo.actions.
 ;; Note: Code and Releases can currently not be deactivated. If you specify default repo units you should still list them for future compatibility.
 ;; External wiki and issue tracker can't be enabled by default as it requires additional settings.
 ;; Disabled repo units will not be added to new repositories regardless if it is in the default list.

docs/content/doc/administration/config-cheat-sheet.en-us.md

@@ -103,8 +103,8 @@ In addition there is _`StaticRootPath`_ which can be set as a built-in at build
 - `DEFAULT_CLOSE_ISSUES_VIA_COMMITS_IN_ANY_BRANCH`:  **false**: Close an issue if a commit on a non default branch marks it as closed.
 - `ENABLE_PUSH_CREATE_USER`:  **false**: Allow users to push local repositories to Gitea and have them automatically created for a user.
 - `ENABLE_PUSH_CREATE_ORG`:  **false**: Allow users to push local repositories to Gitea and have them automatically created for an org.
-- `DISABLED_REPO_UNITS`: **_empty_**: Comma separated list of globally disabled repo units. Allowed values: \[repo.issues, repo.ext_issues, repo.pulls, repo.wiki, repo.ext_wiki, repo.projects\]
-- `DEFAULT_REPO_UNITS`: **repo.code,repo.releases,repo.issues,repo.pulls,repo.wiki,repo.projects,repo.packages**: Comma separated list of default new repo units. Allowed values: \[repo.code, repo.releases, repo.issues, repo.pulls, repo.wiki, repo.projects\]. Note: Code and Releases can currently not be deactivated. If you specify default repo units you should still list them for future compatibility. External wiki and issue tracker can't be enabled by default as it requires additional settings. Disabled repo units will not be added to new repositories regardless if it is in the default list.
+- `DISABLED_REPO_UNITS`: **_empty_**: Comma separated list of globally disabled repo units. Allowed values: \[repo.issues, repo.ext_issues, repo.pulls, repo.wiki, repo.ext_wiki, repo.projects, repo.packages, repo.actions\]
+- `DEFAULT_REPO_UNITS`: **repo.code,repo.releases,repo.issues,repo.pulls,repo.wiki,repo.projects,repo.packages**: Comma separated list of default new repo units. Allowed values: \[repo.code, repo.releases, repo.issues, repo.pulls, repo.wiki, repo.projects, repo.packages, repo.actions\]. Note: Code and Releases can currently not be deactivated. If you specify default repo units you should still list them for future compatibility. External wiki and issue tracker can't be enabled by default as it requires additional settings. Disabled repo units will not be added to new repositories regardless if it is in the default list.
 - `DEFAULT_FORK_REPO_UNITS`: **repo.code,repo.pulls**: Comma separated list of default forked repo units. The set of allowed values and rules is the same as `DEFAULT_REPO_UNITS`.
 - `PREFIX_ARCHIVE_FILES`: **true**: Prefix archive files by placing them in a directory named after the repository.
 - `DISABLE_MIGRATIONS`: **false**: Disable migrating feature.

models/unit/unit.go

@@ -312,7 +312,7 @@ var (
 
 	UnitActions = Unit{
 		TypeActions,
-		"actions.actions",
+		"repo.actions",
 		"/actions",
 		"actions.unit.desc",
 		7,

options/locale/locale_en-US.ini

@@ -1057,6 +1057,7 @@ issues = Issues
 pulls = Pull Requests
 project_board = Projects
 packages = Packages
+actions = Actions
 labels = Labels
 org_labels_desc = Organization level labels that can be used with <strong>all repositories</strong> under this organization
 org_labels_desc_manage = manage