Migration Guide for RTEMS 4.11 to 5

[Sebastian Huber]

Hello,

we started with a migration guide from RTEMS 4.11 (or other versions of 
course) to 5:

https://docs.rtems.org/branches/master/user/migration/v4_11-to-v5.html

There are probably a lot more things to consider. If someone already 
migrated an application to RTEMS 5, then please share your issues, 
workaround, necessary changes, etc. so that others may have it a bit easier.