spec: add missing optional type arguments after TypeName in syntax

Types may be generic, so each occurrence of a TypeName may be
followed by optional type arguments. Add the missing syntactic
(EBNF) factor.

The syntax of type names followed by type arguments matches the
syntax of operand names followed by type arguments (operands may
also be types, or generic functions, among other things). This
opens the door to factoring out this shared syntax, but it will
also require some adjustments to prose to make it work well.
Leaving for another change.

Fixes #53240.

Change-Id: I15212225c28b27f7621e3ca80dfbd131f6b7eada
Reviewed-on: https://go-review.googlesource.com/c/go/+/411918
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of May 12, 2022",
+	"Subtitle": "Version of June 13, 2022",
 	"Path": "/ref/spec"
 }-->
 
@@ -1025,7 +1025,7 @@ <h3 id="Struct_types">Struct types</h3>
 <pre class="ebnf">
 StructType    = "struct" "{" { FieldDecl ";" } "}" .
 FieldDecl     = (IdentifierList Type | EmbeddedField) [ Tag ] .
-EmbeddedField = [ "*" ] TypeName .
+EmbeddedField = [ "*" ] TypeName [ TypeArgs ] .
 Tag           = string_lit .
 </pre>
 
@@ -3029,7 +3029,7 @@ <h3 id="Composite_literals">Composite literals</h3>
 <pre class="ebnf">
 CompositeLit  = LiteralType LiteralValue .
 LiteralType   = StructType | ArrayType | "[" "..." "]" ElementType |
-                SliceType | MapType | TypeName .
+                SliceType | MapType | TypeName [ TypeArgs ] .
 LiteralValue  = "{" [ ElementList [ "," ] ] "}" .
 ElementList   = KeyedElement { "," KeyedElement } .
 KeyedElement  = [ Key ":" ] Element .