Syncing docs to grab color mixer/etc. updates

docs/ja_JP.UTF-8/README.txt

@@ -150,7 +150,19 @@ Tux Paint の起動
 
           [いろ - いろ - くろ、しろ、あか、ぴんく、おれんじ、きいろ、みどり、みずいろ、あお、むらさき、ちゃいろ、はいいろ]
 
-               右端には色についての２つの特別なオプションがあります。スポイトの形をした「カラーピッカー」は描いている絵の中から色を選ぶことができます。また、「レインボーパレット」では、何千もの色から描画色を選ぶことができます。
+               On the far right are three special color options:
+                  * The "color picker" (which has an outline of an
+                    eye-dropper) allows you to pick a color found within your
+                    drawing. A shortcut key is available to access this
+                    feature quickly; see below.
+                  * The rainbow palette allows you to pick a color from
+                    within a box containing thousands of colors.
+                  * The "color mixer" (which has silhouette of a paint
+                    palette) allows you to create colors by blending primary
+                    additive colors — red, yellow, and blue — along with
+                    white (to "tint"), grey (to "tone"), and black (to
+                    "shade"). The ratios of colors added are shown at the
+                    bottom.
 
                When the active tool supports colors, a shortcut may be used
                to access the "color picker" option more quickly. Hold the