Fixed build
remove obsolete note on monolog.logger tag
Merge pull request #2991 from WouterJ/build_error

[2.1] Fixed Build errors
Merge branch '2.1' into 2.2

Conflicts:
	reference/constraints/UniqueEntity.rst
Merge pull request #3006 from havvg/2.1

remove obsolete note on monolog.logger tag
Merge remote-tracking branch 'origin/2.1' into 2.2
Merge branch '2.2' into 2.3