[css-values-5] Add missing ? from some grammars, and reformat for readability. #6245

Author: tabatkins

css-values-5/Overview.bs

@@ -1035,7 +1035,10 @@ Global Syntax of the *-interpolate() family</h3>
 				&& <<easing-function>>? && <<segment-options>>?
 			] ,
 			<<input-position>>{1,2} : <<output-value>> ,
-			[ [ <<easing-function>> || <<segment-options>> ]? , <<input-position>>{1,2} : <<output-value>> ]#?
+			[
+				[ <<easing-function>> || <<segment-options>> ]? ,
+				<<input-position>>{1,2} : <<output-value>>
+			]#?
 		)
 	</pre>
 
@@ -1273,7 +1276,7 @@ Interpolated Numeric and Dimensional Values: the ''calc-interpolate()'' notation
 				&& <<easing-function>>?
 			] ,
 			<<input-position>>{1,2} : <<calc-sum>> ,
-			[ <<easing-function>>? , <<input-position>>{1,2} : <<calc-sum>> ]# )
+			[ <<easing-function>>? , <<input-position>>{1,2} : <<calc-sum>> ]#? )
 	</pre>
 
 	The <<calc-sum>> arguments can resolve
@@ -1297,8 +1300,10 @@ Interpolated Color Values: the ''color-interpolate()'' notation</h3>
 				&& <<easing-function>>? && <<color-interpolation-method>>?
 			] ,
 			<<input-position>>{1,2} : <<color>>,
-			[ [ <<easing-function>> || <<color-interpolation-method>> ],
-			  <<input-position>>{1,2} : <<color>> ]# )
+			[
+				[ <<easing-function>> || <<color-interpolation-method>> ],
+				<<input-position>>{1,2} : <<color>>
+			]#? )
 	</pre>
 
 <h3 id="transform-interpolate">
@@ -1315,7 +1320,7 @@ Interpolated Transform Values: the ''transform-interpolate()'' notation</h3>
 				&& <<easing-function>>?
 			],
 			<<input-position>>{1,2} : <<transform-list>>,
-			[ <<easing-function>>?, <<input-position>>{1,2} : <<transform-list>> ]# )
+			[ <<easing-function>>?, <<input-position>>{1,2} : <<transform-list>> ]#? )
 	</pre>
 
 	''transform-interpolate()'' is, itself, a <<transform-function>>.
@@ -1334,10 +1339,10 @@ Interpolated Property Values: the ''interpolate()'' notation</h3>
 				&& <<easing-function>>?
 			] ,
 			<<input-position>>{1,2} : <<whole-value>>,
-			[ <<easing-function>>?, <<input-position>>{1,2} : <<whole-value>> ]# ) |
-		interpolate( <<progress-source>> && [ by <<easing-function>> ]?
-			&& <<easing-function>>?
-			of <<keyframes-name>> )
+			[ <<easing-function>>?, <<input-position>>{1,2} : <<whole-value>> ]#? )
+		|
+			interpolate( <<progress-source>> && [ by <<easing-function>> ]?
+				&& <<easing-function>>? of <<keyframes-name>> )
 	</pre>
 
 	The first syntax alternative, like other [=interpolation notations=],