Fix accidental /// comments and a docs typo (#64287)

## Objective

Fix small comment/docs typos left out of #64282.

## Solution

- Replace accidental Rust-style `///` comments with `//` in
`assets/settings/default.json` (`git_panel.tree_view` and
`git.gutter_debounce`)
- Fix typo in `docs/src/visual-customization.md`:
`"enable_language_server" if false` ? `is false`

## Testing

Comment/docs-only changes; no runtime behavior change.

---

Release Notes:

- N/A

Co-authored-by: Cursor <cursoragent@cursor.com>

assets/settings/default.json

@@ -1100,9 +1100,9 @@
     //
     // Default: false
     "collapse_untracked_diff": false,
-    /// Whether to show entries with tree or flat view in the panel
-    ///
-    /// Default: false
+    // Whether to show entries with tree or flat view in the panel
+    //
+    // Default: false
     "tree_view": false,
     // Whether the git panel should open on startup.
     //
@@ -1783,9 +1783,9 @@
     // 2. Hide the gutter
     //      "git_gutter": "hide"
     "git_gutter": "tracked_files",
-    /// Sets the debounce threshold (in milliseconds) after which changes are reflected in the git gutter.
-    ///
-    /// Default: 0
+    // Sets the debounce threshold (in milliseconds) after which changes are reflected in the git gutter.
+    //
+    // Default: 0
     "gutter_debounce": 0,
     // Control whether the git blame information is shown for the currently
     // focused line, and where it is rendered.

docs/src/visual-customization.md

@@ -370,7 +370,7 @@ TBD: Centered layout related settings
   "global_lsp_settings": {
     // Show/hide the LSP button in the status bar.
     // Activity from the LSP is still shown.
-    // Button is not shown if "enable_language_server" if false.
+    // Button is not shown if "enable_language_server" is false.
     "button": true
   },
 ```