Fix meta description so that embeds are properly formatted

[matthewpereira]

Currently we have a placeholder description that will show up if someone copy/pastes the URL into Discord (and likely also in Twitter, Slack, etc).

We should audit this and craft the right meta data so that the project logo and description show up correctly.

Side note: the title is also repeating needlessly on the homepage.

[aaguiarz]

The home page title should be <title>OpenFGA | Fine Grained Authorization</title>

[adriantam]

The home page title should be <title>OpenFGA | Fine Grained Authorization</title>

Note that in Docusaurus, each page's title in metadata will be " | ". This is not something that is customizable at this moment.

As such, the home page title should be
The home page title should be <title>Fine Grained Authorization | OpenFGA</title> instead.