docs(ui-top-nav-bar): fix runtime crash in v2 "Full width dialog" example

The in-place search dialog example passed its shared-token override through the
`theme` prop, which deep-merges straight into the theme and replaced the
`sharedTokens` function with a plain object. When the TextInput computed its
style it called `theme.newTheme.sharedTokens?.(semantics)` and threw
"theme.newTheme.sharedTokens is not a function".

Pass the override via the `themeOverride` prop instead. It is applied separately
and deep-merged into the result of `sharedTokens(semantics)`, leaving the
function intact. Matches the InstUISettingsProvider JSDoc and the Link v2 README.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: git-nandor

packages/ui-top-nav-bar/src/TopNavBar/v2/README.md

@@ -2137,16 +2137,13 @@ class InPlaceDialogExample extends React.Component {
                   content: ({ closeInPlaceDialog }) => (
                     <View as="div" padding="general.spaceSm">
                       <InstUISettingsProvider
-                        theme={(currentTheme) => ({
-                          newTheme: {
-                            sharedTokens: {
-                              focusOutline: {
-                                ...currentTheme?.newTheme?.sharedTokens?.focusOutline,
-                                infoColor: 'white'
-                              }
+                        themeOverride={{
+                          sharedTokens: {
+                            focusOutline: {
+                              infoColor: 'white'
                             }
                           }
-                        })}
+                        }}
                       >
                         <TextInput
                           id="searchInput"