go.tools/cmd/godoc/static: fix text template for variable examples.

Fixes golang/go#7771.

LGTM=bgarcia
R=golang-codereviews, bradfitz, bgarcia
CC=golang-codereviews
https://golang.org/cl/87180044

godoc/static/package.txt

@@ -61,7 +61,7 @@ package {{.Name}}
 
 */}}{{if .Vars}}{{range .Vars}}{{node $ .Decl}}
 {{comment_text .Doc "    " "\t"}}
-{{example_text $ .Name "    "}}{{end}}{{end}}{{/*
+{{range $name := .Names}}{{example_text $ $name "    "}}{{end}}{{end}}{{end}}{{/*
 
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godoc/static/static.go

@@ -1869,7 +1869,7 @@ package {{.Name}}
 
 */}}{{if .Vars}}{{range .Vars}}{{node $ .Decl}}
 {{comment_text .Doc "    " "\t"}}
-{{example_text $ .Name "    "}}{{end}}{{end}}{{/*
+{{range $name := .Names}}{{example_text $ $name "    "}}{{end}}{{end}}{{end}}{{/*
 
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