docs: Remove Preview callouts for stable release (#50119)

This PR removes Preview callouts from documentation for features that
are now in Stable.

Features documented with Preview callouts are now included in the stable
release.

Generated by script/docs-strip-preview-callouts

Release Notes:

- N/A

docs/src/reference/all-settings.md

@@ -519,8 +519,6 @@ Note: Dirty files (files with unsaved changes) will not be automatically closed
 - `"unified"`: Show changes inline with added and deleted lines stacked vertically
 - `"split"`: Display old and new versions side by side in separate panes (default)
 
-> **Changed in Preview (v0.225).** Values renamed from `"stacked"`/`"side_by_side"` to `"unified"`/`"split"`.
-
 See [Git documentation](../git.md#diff-view-styles) for more details.
 
 ## Disable AI
@@ -2774,8 +2772,6 @@ These values take in the same options as the root-level settings with the same n
 
 ### Document Symbols
 
-> **Preview:** This feature is available in Zed Preview. It will be included in the next Stable release.
-
 - Description: Controls the source of document symbols used for outlines and breadcrumbs.
 - Setting: `document_symbols`
 - Default: `off`
@@ -5140,8 +5136,6 @@ See the [debugger page](../debugger.md) for more information about debugging sup
 
 ## Git Worktree Directory
 
-> **Preview:** This feature is available in Zed Preview. It will be included in the next Stable release.
-
 - Description: Directory where git worktrees are created, relative to the repository working directory.
 - Setting: `git.worktree_directory`
 - Default: `"../worktrees"`

docs/src/reference/cli.md

@@ -71,8 +71,6 @@ zed -n ~/projects/myproject
 
 ### `-a`, `--add`
 
-> **Changed in Preview (v0.225).** See [release notes](/releases#0.225).
-
 Add paths to the currently focused workspace instead of opening a new window. When multiple workspace windows are open, files open in the focused window:
 
 ```sh