Fixed typo in doc of juce_SpinLock.h

modules/juce_core/threads/juce_SpinLock.h

@@ -29,7 +29,7 @@ namespace juce
     uncontended situations.
 
     Note that unlike a CriticalSection, this type of lock is not re-entrant, and may
-    be less efficient when used it a highly contended situation, but it's very small and
+    be less efficient when used in a highly contended situation, but it's very small and
     requires almost no initialisation.
     It's most appropriate for simple situations where you're only going to hold the
     lock for a very brief time.