[css-flexbox] Update DoC

Author: fantasai

css-flexbox/issues-lc-20150514.txt

@@ -68,3 +68,10 @@ Summary:  Broken Styling
 From:     Ryan Prichard
 Comment:  http://www.w3.org/mid/CA+gYnHRp6RC4OECQTicZGSGB_Rq=x+3O8P3mVD=gCY+g0u8EoA@mail.gmail.com
 ----
+Issue 11.
+Summary:  Blink objects to percentage-margin change
+From:     Tab Atkins Jr.
+Comment:  https://lists.w3.org/Archives/Public/www-style/2015Feb/0521.html
+Note:     Accepting this reversal will require a corresponding change to Grid.
+Open
+----