25530-sumdb.md: fix a typo in the endpoint reference

Change-Id: Icbf807364f64585d23ca2e36b919aeb57a068f1b
Reviewed-on: https://go-review.googlesource.com/c/proposal/+/189320
Reviewed-by: Andrew Bonventre <andybons@golang.org>
diff --git a/design/25530-sumdb.md b/design/25530-sumdb.md
index d21bf78..c1f1647 100644
--- a/design/25530-sumdb.md
+++ b/design/25530-sumdb.md
@@ -197,7 +197,7 @@
    (with a literal `data` path element).
 Clients are expected to use `/lookup` and `/tile/H/L/...` during normal operations,
-while auditors will want to use `/latest` and `/tile/L/data/...`.
+while auditors will want to use `/latest` and `/tile/H/data/...`.
 A special `go` command may also fetch `/latest` to force incorporation
 of that signed tree head into the local timeline.