[gnome-shell/wip/carlosg/grabs-pt2] js/main: Add docs to private function

[Carlos Garnacho <carlosg src gnome org>]

commit 4e6ad11a9b5c15c5256799bdcab1cb6053775bed
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Jan 29 01:14:56 2022 +0100

    js/main: Add docs to private function
    
    Oh, well...

 js/ui/main.js | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/js/ui/main.js b/js/ui/main.js
index 14a541f0a6..20cb887da4 100644
--- a/js/ui/main.js
+++ b/js/ui/main.js
@@ -503,6 +503,13 @@ function notifyError(msg, details) {
     notify(msg, details);
 }
 
+/**
+ * _findModal:
+ * @param {Clutter.Grab} grab - grab
+ *
+ * Private function.
+ *
+ */
 function _findModal(grab) {
     for (let i = 0; i < modalActorFocusStack.length; i++) {
         if (modalActorFocusStack[i].grab === grab)