last updates the mutexes keynote presentation

Author: steevehook

mutexes/README.md

@@ -112,10 +112,11 @@ the database consistency which otherwise is not possible for a non-serial schedu
 - [Mutual Exclusion - Wiki](https://en.wikipedia.org/wiki/Mutual_exclusion)
 - [Dining Philosophers Problem - Wiki](https://en.wikipedia.org/wiki/Dining_philosophers_problem)
 - [Test and Set - Wiki](https://en.wikipedia.org/wiki/Test-and-set)
-- [Monitor - Wiki](https://en.wikipedia.org/wiki/Monitor_(synchronization))
 - [Tuple Space - Wiki](https://en.wikipedia.org/wiki/Tuple_space)
 - [Message Passing - Wiki](https://en.wikipedia.org/wiki/Message_passing)
 - [Semaphore - Wiki](https://en.wikipedia.org/wiki/Semaphore_(programming))
+- [Monitor - Wiki](https://en.wikipedia.org/wiki/Monitor_(synchronization))
+- [Spinlock - Wiki](https://en.wikipedia.org/wiki/Spinlock)
 - [Concurrency Control - Wiki](https://en.wikipedia.org/wiki/Concurrency_control)
 - [Serializability - Wiki](https://en.wikipedia.org/wiki/Serializability)
 - [Serializability in DBMS - Educba](https://www.educba.com/serializability-in-dbms/)