bug #15981 [Form] Update form_collections.rst (Punt13140)

This PR was submitted for the 5.4 branch but it was merged into the 5.3 branch instead.

Discussion
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[Form] Update form_collections.rst

Hi,

I followed the instruction, and if you add a delete button to the `<ul>` parent, you have a delete button with no `li` to delete.

Thanks

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Commits
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4800824 Update form_collections.rst

Author: wouterj

form/form_collections.rst

@@ -531,7 +531,7 @@ First, add a "delete this tag" link to each tag form:
 
 .. code-block:: javascript
 
-    const tags = document.querySelectorAll('ul.tags')
+    const tags = document.querySelectorAll('ul.tags li')
     tags.forEach((tag) => {
         addTagFormDeleteLink(tag)
     })