InlineAlert title should be header

# 🙋 Documentation Request

Hi, there!

The `InlineAlert` section of the `README.md` file mentions the `title` slot a few times (lines 1591, 1614) but the only example that actually works (line 1628) uses `header`.

If they're both supposed to work, then there's a bug with `title`; otherwise, if `header` is the correct one (which I can confirm), all `title` instances should be replaced with `header`.

## 🧢 Your Company/Team

DevEx

Open README.md and inspect the InlineAlert section around lines 1591, 1614, and 1628. Confirm that the working example uses header, then update the documented slot references if header is the supported name; done means the section consistently matches the working example.

Written by the indexing model from the issue text.