Update link in MINAR_migration.md

Change link from 5.3 to 5.5

Author: Amanda Butler

docs/advanced/MINAR_migration.md

@@ -63,7 +63,7 @@ If you don't like asynchronous programming, or if you wrote your code in asynchr
 To help ease porting MINAR applications, and to provide support for asynchronous style programming, mbed OS 5 provides an optional event loop. The main documentation for the event loop can be found [here](https://docs.mbed.com/docs/mbed-os-api-reference/en/5.5/APIs/tasks/events/). In short, the mbed OS 5 event loop implementation consists of an [EventQueue class](https://github.com/ARMmbed/mbed-os/blob/master/events/EventQueue.h) that implements the storage for the events and has a `dispatch` function. There are differences between MINAR and `EventQueue`:
 
 - MINAR and the mbed OS 5 event loop have incompatible APIs.
-- Both MINAR and `EventQueue` work with *events* (objects that are placed in the event queue). However, the interface and implementations of events in MINAR and mbed OS 5 are different, and that's also true for the APIs that use them. Look at [the Callback class](https://docs.mbed.com/docs/mbed-os-api/en/mbed-os-5.3/api/group__drivers.html), [the Event class](https://github.com/ARMmbed/mbed-os/blob/master/events/Event.h) and [the EventQueue class](https://github.com/ARMmbed/mbed-os/blob/master/events/EventQueue.h) for more details about the mbed OS 5 implementation.
+- Both MINAR and `EventQueue` work with *events* (objects that are placed in the event queue). However, the interface and implementations of events in MINAR and mbed OS 5 are different, and that's also true for the APIs that use them. Look at [the Callback class](https://docs.mbed.com/docs/mbed-os-api/en/mbed-os-5.5/api/group__drivers.html), [the Event class](https://github.com/ARMmbed/mbed-os/blob/master/events/Event.h) and [the EventQueue class](https://github.com/ARMmbed/mbed-os/blob/master/events/EventQueue.h) for more details about the mbed OS 5 implementation.
 - In mbed OS 3, the startup code automatically starts the event loop's `dispatch` function. In mbed OS 5, the event loop is optional, so the programmer must initialize and start it manually. The event loop documentation has more information on this topic.
 - MINAR runs on top of a hardware timer, but `EventQueue::dispatch` runs (typically) in its own RTOS thread.
 - mbed OS 5 can have as many event loops as needed, each running in its own thread.