docs: fix the default value of Popper's boundary option (#33685)

`'scrollParent'` is no longer the default `boundary` value

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

site/content/docs/5.0/components/tooltips.md

@@ -116,12 +116,12 @@ var tooltip = new bootstrap.Tooltip(exampleEl, options)
 {{< callout warning >}}
 ##### Overflow `auto` and `scroll`
 
-Tooltip position attempts to automatically change when a parent container has `overflow: auto` or `overflow: scroll` like our `.table-responsive`, but still keeps the original placement's positioning. To resolve, set the `boundary` option to anything other than default value, `'scrollParent'`, such as `'window'`:
+Tooltip position attempts to automatically change when a **parent container** has `overflow: auto` or `overflow: scroll` like our `.table-responsive`, but still keeps the original placement's positioning. To resolve this, set the [`boundary` option](https://popper.js.org/docs/v2/modifiers/flip/#boundary) (for the flip modifier using the `popperConfig` option) to any HTMLElement to override the default value, `'clippingParents'`, such as `document.body`:
 
 ```js
 var exampleEl = document.getElementById('example')
 var tooltip = new bootstrap.Tooltip(exampleEl, {
-  boundary: 'window'
+  boundary: document.body // or document.querySelector('#boundary')
 })
 ```
 {{< /callout >}}