internal/web: fix syntax rules hyperlinks

The filepath for the spec document changed and broke
the linkify step.

Fixes golang/go#50915

Change-Id: Ieafe9c665f4063fb9f9ddf74610925f123e2c249
Reviewed-on: https://go-review.googlesource.com/c/website/+/388859
Run-TryBot: Jamal Carvalho <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Trust: Jamal Carvalho <[email protected]>

Author: jamalc

cmd/golangorg/testdata/web.txt

@@ -339,6 +339,9 @@ redirect == https://go.dev/ref/spec
 GET https://go.dev/ref/spec
 body contains Go Programming Language Specification
 
+GET https://go.dev/ref/spec
+body contains <a id="assign_op">assign_op</a>
+
 GET https://golang.org/robots.txt
 redirect == https://go.dev/robots.txt
 

internal/web/site.go

@@ -525,7 +525,7 @@ func (s *Site) serveHTML(w http.ResponseWriter, r *http.Request, p *pageFile) {
 	}
 
 	// if it's the language spec, add tags to EBNF productions
-	if strings.HasSuffix(filePath, "go_spec.html") {
+	if strings.HasSuffix(filePath, "ref/spec.html") {
 		var buf bytes.Buffer
 		spec.Linkify(&buf, []byte(src))
 		src = buf.String()