[docs] Better explain what happens in the future

[oliviertassinari]

Preview: https://deploy-preview-2036--material-ui-x.netlify.app/components/data-grid/getting-started/#license-key-installation

Try to solve this pain point:

Hi,

my company, XXX, just bought PRO licences of MaterialUI.
We received an email with the key and an expiry date in one year.

As developers we need to know how to integrate this key in our apps but we do not know what will occur in one year if we strictly follow the instructions in the "licence key installation" documentation.
Can you please elaborate on what will occur so that we can elaborate a strategy to integrate the key in pour apps.

Thanks.

They had already found https://material-ui.com/components/data-grid/getting-started/#license-key-installation

[McFoggy]

Thank you Olivier that clarifies the whole thing and answer our questions.

[oliviertassinari]

It might duplicate a bit with the content on the pricing page and its FAQ but since the question was technical and not sales-related, I think that it's a safe improvement.