Add /index.html to unadorned alias paths

Bring code to be better in line with documentation.

target/alias_test.go

@@ -13,9 +13,13 @@ func TestHTMLRedirectAlias(t *testing.T) {
 		expected string
 	}{
 		{"", ""},
-		{"alias 1", "alias-1"},
+		{"s", "s/index.html"},
+		{"/", "/index.html"},
+		{"alias 1", "alias-1/index.html"},
 		{"alias 2/", "alias-2/index.html"},
 		{"alias 3.html", "alias-3.html"},
+		{"alias4.html", "alias4.html"},
+		{"/alias 5.html", "/alias-5.html"},
 	}
 
 	for _, test := range tests {