Add TTL as a common initialism.
diff --git a/lint.go b/lint.go
index d22a4af..31fb872 100644
--- a/lint.go
+++ b/lint.go
@@ -437,6 +437,7 @@
 	"RAM":   true,
 	"RHS":   true,
 	"RPC":   true,
+	"TTL":   true,
 	"UI":    true,
 	"UID":   true,
 	"URL":   true,