added note of breaking change to readme

7 jobs for cmdline_breakingBatch in 42 minutes and 34 seconds
Status Job ID Name Coverage
  Test
passed #26116
Apple
Mac-Cpp11

00:38:07

passed #26115
Qt551 VS2013
VS2013-Qt-5.5.1-x64

00:20:02

passed #26114
Qt56 VS2015
VS2015-Qt-5.6.0-x32

00:26:01

passed #26113
Qt56 VS2015
VS2015-Qt-5.6.0-x64

00:22:30

passed #26111
MultiThreads Linux
clang-c++11-Qt5

00:10:51

passed #26112
MultiThreads Linux
cppcheck

00:03:47

passed #26110
Linux
gcc-c++11-Qt5

00:02:46