Fix punctuation in ES.77
diff --git a/CppCoreGuidelines.md b/CppCoreGuidelines.md
index 179718c52..e451ece87 100644
--- a/CppCoreGuidelines.md
+++ b/CppCoreGuidelines.md
@@ -12634,7 +12634,7 @@ Often, a loop that requires a `break` is a good candidate for a function (algori
 
     ???
 
-Often. a loop that uses `continue` can equivalently and as clearly be expressed by an `if`-statement.
+Often, a loop that uses `continue` can equivalently and as clearly be expressed by an `if`-statement.
 
     ???
 
