Replace old hilla.dev links

[veerapaananen]

Old hilla.dev links redirect to vaadin.com now. This fix replaces those links in the latest Docs content with the final addresses they currently redirect to, removing the old links pointing to hilla.dev and removing redirections.

Example:

• Old link: https://hilla.dev
• New link: https://vaadin.com/hilla

[CLAassistant]

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1 out of 2 committers have signed the CLA.

✅ peholmst
❌ Veera Paananen

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