spec: allow range-over-func to omit iteration variables

For #65236.

Change-Id: I5a11811cc52467ea4446db29c3f86b119f9b2409
Reviewed-on: https://go-review.googlesource.com/c/go/+/592295
Reviewed-by: Robert Griesemer <[email protected]>
Auto-Submit: Robert Griesemer <[email protected]>
TryBot-Bypass: Robert Griesemer <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: griesemer

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Language version go1.23 (June 4, 2024)",
+	"Subtitle": "Language version go1.23 (June 12, 2024)",
 	"Path": "/ref/spec"
 }-->
 
@@ -6733,8 +6733,6 @@ <h4 id="For_range">For statements with <code>range</code> clause</h4>
 <code>f</code> returns.
 If the loop body terminates (such as by a <code>break</code> statement),
 <code>yield</code> returns false and must not be called again.
-The number of iteration variables must match the number and order of arguments
-to <code>yield</code>.
 </li>
 </ol>