Update HMR docs

[alexeyr-ci]

E.g. we have

react_on_rails/docs/guides/hmr-and-hot-reloading-with-the-webpack-dev-server.md

Line 34 in 846d02d

`dev_server.inline` maps to [devServer.inline](https://webpack.js.org/configuration/dev-server/#devserverinline).

but devServer.inline doesn't seem to exist and the option may have been removed on our side too.

[justin808]

@claude can you update this doc file. Create a PR.

[claude]

Claude finished @justin808's task —— View job • claude/issue-1682-20250924-2356 • Create PR ➔

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Completed updating HMR documentation ✓

Todo List:

• Read the current HMR documentation file
• Identify outdated webpack dev server configurations
• Update the documentation to reflect current webpack options
• Commit and push changes
• Provide PR creation link

Summary

I've successfully updated the HMR documentation to remove all references to the deprecated devServer.inline option, which no longer exists in webpack 5. The changes include:

• Removed devServer.inline configuration references from lines 35-36
• Removed the inline: true setting from the YAML configuration example
• Removed the associated error message for inline configuration
• Simplified the documentation to only mention the hmr setting

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Branch: claude/issue-1682-20250924-2356