C.31: Improve language just a bit (#1772)

CppCoreGuidelines.md

@@ -4943,7 +4943,7 @@ For resources represented as classes with a complete set of default operations,
 
 ##### Note
 
-What about a sockets that won't close? A destructor, close, or cleanup operation [should never fail](#Rc-dtor-fail).
+What about a socket that won't close? A destructor, close, or cleanup operation [should never fail](#Rc-dtor-fail).
 If it does nevertheless, we have a problem that has no really good solution.
 For starters, the writer of a destructor does not know why the destructor is called and cannot "refuse to act" by throwing an exception.
 See [discussion](#Sd-never-fail).