Add info to the CodingStyle for C++ constructors

Signed-off-by: Thiago Macieira <thiago@macieira.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

CodingStyle

@@ -50,6 +50,14 @@
 	b = a + (c + d +
 		 f + z);
 
+- in a C++ constructor initialization list, the colon is on the same line and
+  continuation lines are aligned as the rule above:
+
+	ClassName::ClassName() : x(1), y(2),
+				 z(3)
+	{
+	}
+
 - unfortunate inconsistency:
   -- C code usually uses underscores to structure names