Update features.html

[JohnVeness]

I took a look at the https://godotengine.org/features/ page and have made a PR with some suggested changes. Mostly I have made a few minor tweaks to wording/punctuation, and added a couple of links.

A bigger change I've put in this PR is to remove the "New in 4.0" texts as 4.0 isn't particularly new now, so it made the page seem a little dated. If that was too bold of me, then I would suggest "New in Godot 4" instead, as at least that doesn't pick a particular old-sounding point release.

There's a couple of things that I haven't done which I would appreciate some input on:

1. I haven't kept up with the latest, but should the "Leverage your C# experience to feel right at home" section be updated with info about C# web support, or is that still something to "be added in the future"?
2. Should the C++/GDExtension text be moved into a separate section (like the existing sections for GDScript and C#), rather than in the "Pick from a variety of community-supported languages" box?

[raulsntos]

should the "Leverage your C# experience to feel right at home" section be updated with info about C# web support, or is that still something to "be added in the future"?

As of 4.5, C# exports still don't support the web platform. PR that adds support is godotengine/godot#106125 but it's not finished. I'll keep this page in mind when the PR is merged, so we don't forget to update it. Thanks for the reminder.

[hsvfan-jan]

I think this PR could tackle #1123