[Extension API Documentation]Browser Action - Badge

Badges no longer support opacity settings on colors.
Updated documentation to reflect this.

Bug: 623573
Change-Id: I850e3f91980e2ab74efaf795c00cdcdbb749315d
Reviewed-on: https://chromium-review.googlesource.com/979072Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Crystal Lambert <crystallambert@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545821}

chrome/common/extensions/api/browser_action.json

@@ -237,7 +237,7 @@
             "type": "object",
             "properties": {
               "color": {
-                "description": "An array of four integers in the range [0,255] that make up the RGBA color of the badge. For example, opaque red is <code>[255, 0, 0, 255]</code>. Can also be a string with a CSS value, with opaque red being <code>#FF0000</code> or <code>#F00</code>.",
+                "description": "An array of four integers in the range [0,255] that make up the RGBA color of the badge. Can also be a string with a CSS value, red being <code>#FF0000</code> or <code>#F00</code>. Renders colors at full opacity.",
                 "choices": [
                   {"type": "string"},
                   {"$ref": "ColorArray"}