Editorial: Fix Promise.try preamble (#3454)

(Make it consistent with PR #2592)

spec.html

@@ -48148,7 +48148,7 @@ <h1>
 
       <emu-clause id="sec-promise.try">
         <h1>Promise.try ( _callback_, ..._args_ )</h1>
-        <p>When the `try` method is called with argument _callback_, the following steps are taken:</p>
+        <p>This function performs the following steps when called:</p>
         <emu-alg>
           1. Let _C_ be the *this* value.
           1. If _C_ is not an Object, throw a *TypeError* exception.