Fix spelling in comments

Should be non-functional, except for some error message strings.

modules/ca/src/client/searchTimer.cpp

@@ -317,7 +317,7 @@ void searchTimer :: show ( unsigned level ) const
 
 //
 // Reset the delay to the next search request if we get
-// at least one response. However, dont reset this delay if we
+// at least one response. However, don't reset this delay if we
 // get a delayed response to an old search request.
 //
 void searchTimer::uninstallChanDueToSuccessfulSearchResponse (