Remove continuity descriptions from steps(...) (mdn#18482)

As per the spec (https://drafts.csswg.org/css-easing/#step-easing-functions), Figure 5, all step functions are right-continuous (i.e. You'd encounter solid dots approaching discontinuity from the right side). The `direction` keyword should strictly describe when the jumps (i.e. discontinuities) happen.

files/en-us/web/css/easing-function/index.md

@@ -109,11 +109,11 @@ where:
   - : Is a strictly positive {{cssxref("<integer>")}}, representing the amount of equidistant treads composing the stepping function.
 - _direction_
 
-  - : Is a keyword indicating if it the function is [left- or right-continuous](https://en.wikipedia.org/wiki/Left-continuous#Directional_and_semi-continuity):
+  - : Is a keyword indicating when the jumps occur:
 
-    - `jump-start` denotes a left-continuous function, so that the first step or jump happens when the interpolation begins;
-    - `jump-end` denotes a right-continuous function, so that the last step or jump happens when the interpolation ends;
-    - `jump-both` denotes a right and left continuous function, includes pauses at both the 0% and 100% marks, effectively adding a step during the interpolation iteration;
+    - `jump-start` denotes that the first step or jump happens when the interpolation begins;
+    - `jump-end` denotes that the last step or jump happens when the interpolation ends;
+    - `jump-both` denotes that jumps occur at both the 0% and 100% marks, effectively adding a step during the interpolation iteration;
     - `jump-none` There is no jump on either end. Instead, holding at both the 0% mark and the 100% mark, each for 1/n of the duration
     - `start` is the equivalent of `jump-start`
     - `end` is the equivalent of `jump-end`