[css-properties-values-api] Move the @supports text from the JS API to the general section, replacing the note I had left in the general section.

Author: tabatkins

css-properties-values-api/Overview.bs

@@ -293,12 +293,24 @@ which can start or interrupt a CSS transition.
 Conditional Rules {#conditional-rules}
 --------------------------------------
 
-<div class=note>
-	''@supports'' rules and the {{CSS/supports(conditionText)|CSS.supports()}} method
-	behave as specified in [[!css-variables]],
-	without distinguishing between registered and unregistered custom properties,
-	and paying no attention to registered properties' syntaxes.
-</div>
+Unregistered custom properties are “always valid”
+when tested via ''@supports'';
+a rule like `@supports (--foo: red) {...}`
+is always true
+so long as you don't violate the (very liberal) syntax for custom properties.
+
+Registering a custom property does not change this.
+Even if a custom property is, for example,
+registered with `syntax: "&lt;color>"`,
+a rule like `@supports (--foo: 1em) {...}`
+will still evaluate as true and apply those styles.
+
+Note: This matches the [[#parsing-custom-properties|parsing behavior]] of registered custom properties.
+A registered custom property specified as `"&lt;color>"`
+but written as `--foo: 1em;` will still be accepted as valid at parse-time,
+but be automatically [=invalid at computed-value time=].
+As ''@supports'' tests parsing behavior,
+it thus also accepts all values as valid regardless of the registered syntax.
 
 Relative URLs {#relative-urls}
 ------------------------------
@@ -735,28 +747,6 @@ following members:
 ::  The initial value of this custom property.
 
 
-Registered Properties and @supports {#supports}
------------------------------------------------
-
-Unregistered custom properties are “always valid”
-when tested via ''@supports'';
-a rule like `@supports (--foo: red) {...}`
-is always true
-so long as you don't violate the (very liberal) syntax for custom properties.
-
-Registering a custom property does not change this.
-Even if a custom property is, for example,
-registered with `syntax: "&lt;color>"`,
-a rule like `@supports (--foo: 1em) {...}`
-will still evaluate as true and apply those styles.
-
-Note: This matches the parsing behavior of registered custom properties.
-A registered custom property specified as `"&lt;color>"`
-but written as `--foo: 1em;` will still be accepted as valid at parse-time,
-but be automatically [=invalid at computed-value time=].
-As ''@supports'' tests parse behavior,
-it thus also accepts all values as valid regardless of the registered syntax.
-
 Dependency Cycles Via Relative Units {#dependency-cycles}
 ---------------------------------------------------------