Add build status to README.md

1 job for master in 60 minutes and 15 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
failed #73343
linux kf5-qt5 qt5.12

01:00:15

 
Name Stage Failure
failed
linux kf5-qt5 qt5.12 Build The script exceeded the maximum execution time set for the job
      after 542 requests (542 known processed) with 0 events remaining.
kdeinit5: Fatal IO error: client killed
kdeinit5: sending SIGHUP to children.
klauncher: Exiting on signal 1
The X11 connection broke (error 1). Did the X11 server die?
$ python3 -u $CI_TOOLING/helpers/print-lcov-results.py --product $PRODUCT --project $PROJECT --branchGroup $BRANCH_GROUP --platform $PLATFORM
kdeinit5: sending SIGTERM to children.
kdeinit5: Exit.
ERROR: Job failed: execution took longer than 1h0m0s seconds