chore(tools): Fix doc inclusion tools on Windows (#13685)

tools/config_includer/generator.go

@@ -91,7 +91,7 @@ func main() {
 
 		newUnresolved := make(map[string]string)
 		for name, fn := range unresolved {
-			if filepath.IsAbs(fn) {
+			if strings.HasPrefix(filepath.ToSlash(fn), "/") {
 				fn = filepath.Join(root, fn)
 			}
 
@@ -121,7 +121,7 @@ func main() {
 			pwd = string(filepath.Separator) + pwd
 			for _, iname := range extractIncludes(tmpl) {
 				ifn := iname
-				if !filepath.IsAbs(ifn) {
+				if !strings.HasPrefix(ifn, "/") {
 					ifn = filepath.Join(pwd, ifn)
 				}
 				newUnresolved[iname] = ifn

tools/readme_config_includer/generator.go

@@ -52,10 +52,9 @@ func extractIncludeBlock(txt []byte, includesEx *regexp.Regexp, root string) *in
 		if len(inc) != 2 {
 			continue
 		}
-		include := filepath.FromSlash(string(inc[1]))
+		include := string(inc[1])
 		// Make absolute paths relative to the include-root if any
-		// Check original value to avoid platform specific slashes
-		if filepath.IsAbs(string(inc[1])) {
+		if strings.HasPrefix(include, "/") {
 			if root == "" {
 				log.Printf("Ignoring absolute include %q without include root...", include)
 				continue