spec: clarify prose in rule for clear built-in

Per feedback on #56351.

For #56351.

Change-Id: I63dd1713a1efe4d7180d932dbd8e1510cbb32e90
Reviewed-on: https://go-review.googlesource.com/c/go/+/510935
TryBot-Bypass: Robert Griesemer <[email protected]>
Auto-Submit: Robert Griesemer <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>

Author: griesemer

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of June 14, 2023",
+	"Subtitle": "Version of July 19, 2023",
 	"Path": "/ref/spec"
 }-->
 
@@ -7324,7 +7324,8 @@ <h3 id="Clear">Clear</h3>
 </pre>
 
 <p>
-If the argument type is a <a href="#Type_parameter_declarations">type parameter</a>,
+If the type of the argument to <code>clear</code> is a
+<a href="#Type_parameter_declarations">type parameter</a>,
 all types in its type set must be maps or slices, and <code>clear</code>
 performs the operation corresponding to the actual type argument.
 </p>