Adjust a thread annotation.

Change-Id: Ib7867190116fbc65d404804c4f14392f599d8bd3
Reviewed-on: https://code-review.googlesource.com/c/re2/+/44510
Reviewed-by: Paul Wankadia <junyer@google.com>
diff --git a/re2/dfa.cc b/re2/dfa.cc
index 77a1fb6..f0d342a 100644
--- a/re2/dfa.cc
+++ b/re2/dfa.cc
@@ -1138,8 +1138,8 @@
   mu_->ReaderLock();
 }
 
-// This function is marked as NO_THREAD_SAFETY_ANALYSIS because the annotations
-// does not support lock upgrade.
+// This function is marked as NO_THREAD_SAFETY_ANALYSIS because
+// the annotations don't support lock upgrade.
 void DFA::RWLocker::LockForWriting() NO_THREAD_SAFETY_ANALYSIS {
   if (!writing_) {
     mu_->ReaderUnlock();