Fix a typo in service/histograms.xml

This is a follow-up of [1].

[1] https://chromium-review.googlesource.com/c/chromium/src/+/2532161/comment/b7184485_63304094/

Bug: N/A
Change-Id: Icbb987ab9753a817dd64e12f3dd17be7e20919aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537520
Auto-Submit: Kenichi Ishibashi <bashi@chromium.org>
Commit-Queue: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827291}

tools/metrics/histograms/histograms_xml/service/histograms.xml

@@ -1100,7 +1100,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   <owner>chrome-worker@google.com</owner>
   <summary>
     The counts of retries to recover after a Storage Service crash. Logged after
-    a recovery, or the maximum number of retries is exceeded See
+    a recovery, or the maximum number of retries is exceeded. See
     ServiceWorkerRegistry::OnRemoteStorageDisconnected() for the maximum number
     of retries.
   </summary>