unity fix

Author: Suri539

dita/RTC-NG/API/rtc_api_overview_ng.dita

@@ -1034,7 +1034,7 @@
                 <stentry>方法</stentry>
                 <stentry>描述</stentry>
             </sthead>
-            <strow props="flutter rn electron unity">
+            <strow props="flutter rn electron">
                 <stentry><xref keyref="startEchoTest2"/></stentry>
                 <stentry><ph conkeyref="startEchoTest2/shortdesc"/></stentry>
             </strow>