Wifi: Improve documentation for some hidl APIs

This commit improves some of the comments for the Wifi Hidl APIs.

Bug: 148236141
Test: No test is done
Change-Id: Iff6b191c8b258615ddaacad570b81f0ada968ed4
diff --git a/wifi/1.2/IWifiStaIface.hal b/wifi/1.2/IWifiStaIface.hal
index 3a7f777..d65b33b 100644
--- a/wifi/1.2/IWifiStaIface.hal
+++ b/wifi/1.2/IWifiStaIface.hal
@@ -23,7 +23,7 @@
 /**
  * Interface used to represent a single STA iface.
  *
- * IWifiChip.createStaIface() may return a @1.2::IWifiStaIface when supported.
+ * IWifiChip.createStaIface() must return a @1.2::IWifiStaIface when supported.
  */
 interface IWifiStaIface extends @1.0::IWifiStaIface {
     /**