Remove redundant support query

Created by: MartijnCuppens

The documentation about .sticky-top is incorrect & the I doubt the @support query is really necessary.

IE11 and IE10 will render position: sticky as position: relative.

Nope, it won't. It 'll render as it's initial position value, probably static.

As such, we wrap the styles in a @supports query, limiting the stickiness to only browsers that can render it properly.

If it's not supported, there's not really any difference in using the @support query or not, unless the position is explicitly set to anything else than static. IMO we can remove the support query, it's feels a bit inconsistent to only check for it on that place.