Dual license `bevy-website` with Apache 2.0

[BlackPhlox]

Add Apache 2.0 to bevy-website to be consistent with bevy.

As mentioned by cart, this relicensing would not be as comprehensive as bevy's relicensing.

There are currently 90 contributors that are required to accept the new licensing agreement.

Update counter: 1/90 (89 Left)

[Nilirad]

Make sure to not count dependabot this time!

[rparrett]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.