[scroll-animations-1] Editorial: Drop reference to upcoming threshold value. It appears to already be added to the spec.

Author: birtles

scroll-animations-1/Overview.bs

@@ -596,10 +596,11 @@ The procedure to <dfn>resolve an element-based offset</dfn> given
 <div class="note">
 Note: With threshold 0.0, the algorithm selects the effective scroll offset such
 that the target is adjacent to the [=scrollport=] at the given edge but not yet
-visible. The upcoming threshold value will allow authors to control the amount
-of target that needs to be visible in [=scrollport=]. In particular threshold
-value 1.0 ensure that target is fully visible (as long as [=scrollport=] is
-large enough).
+visible.
+The threshold value allows authors
+to control the amount of target that needs to be visible in [=scrollport=].
+In particular threshold value 1.0 ensure that target is fully visible
+(as long as [=scrollport=] is large enough).
 
 <figure>
 <img src="img/example-element-based-threshold.svg" width="600"