Replace parentheses with curly braces to fix vector doc bug.

https://code.google.com/p/android/issues/detail?id=178299

Change-Id: I3ae31d48a39e8db9976fdedde560e870b23e2c83

docs/html/guide/topics/renderscript/reference/overview.jd

@@ -43,7 +43,7 @@ E.g. <a href='rs_value_types.html#android_rs:float4'>float4</a>, <a href='rs_val
 </p>
 
 <p> To create vector literals, use the vector type followed by the values enclosed
-between parentheses, e.g. <code>(float3)(1.0f, 2.0f, 3.0f)</code>.
+between curly braces, e.g. <code>(float3){1.0f, 2.0f, 3.0f}</code>.
 </p>
 
 <p> Entries of a vector can be accessed using different naming styles.