Add missing full stop.

PiperOrigin-RevId: 281755163
diff --git a/tools/build_defs/repo/http.bzl b/tools/build_defs/repo/http.bzl
index da4bf88..3bf9471 100644
--- a/tools/build_defs/repo/http.bzl
+++ b/tools/build_defs/repo/http.bzl
@@ -189,7 +189,7 @@
         doc = "Location of the .netrc file to use for authentication",
     ),
     "canonical_id": attr.string(
-        doc = """A canonical id of the archive downloaded
+        doc = """A canonical id of the archive downloaded.
 
 If specified and non-empty, bazel will not take a the archive from cache,
 unless is was added to the cache by a request with the same canonical id.