separate README files for separate RHEL versions

deploy_checkit_tiff/centos6/README.txt

+How to build checkit-tiff variants for Redhat 6 system used by Rosetta
+======================================================================
+
+:lang: en
+:encoding: utf-8
+:author: Andreas Romeyke
+
+== Prerequisites
+
+* you need 'docker'
+* If using Debian buster or higher, you must(!) add "vsyscall=emulate" option
+to the Linux kernel boot option, because CentOS 6.xx triggers syscalls in an
+outdated way.
+
+== How to build
+
+# If something was built, delete all containers for specific image:
+docker ps -a | awk '{ print $1,$2 }' | grep checkit-tiff | awk '{print $1 }' | xargs -I {} docker rm {}
+
+# build stuff
+docker build -t checkit-tiff --rm=true ./
+
+== find out which image
+
+docker images
+
+lists:
+REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
+checkit-tiff        latest              acc13d4a83d9        3 minutes ago       827 MB     # <==== that's it!
+<none>              <none>              e3be26e603f0        5 minutes ago       824 MB
+centos              6.10                0cd976dc0a98        10 months ago       195 MB
+
+
+== How to copy already built binaries
+
+id=$(docker create checkit-tiff)
+
+docker cp $id:/tmp/checkit_tiff_current.tgz ./
+docker cp $id:/tmp/checkit_tiff_upcoming.tgz ./
+
+docker rm -v $id
+

deploy_checkit_tiff/centos7/README.txt

+How to build checkit-tiff variants for Redhat 7 system used by Rosetta
+======================================================================
+
+:lang: en
+:encoding: utf-8
+:author: Andreas Romeyke
+
+== Prerequisites
+
+* you need 'docker'
+
+== How to build
+
+# If something was built, delete all containers for specific image:
+docker ps -a | awk '{ print $1,$2 }' | grep checkit-tiff | awk '{print $1 }' | xargs -I {} docker rm {}
+
+# build stuff
+docker build -t checkit-tiff --rm=true ./
+
+== find out which image
+
+docker images
+
+lists:
+REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
+checkit-tiff        latest              acc13d4a83d9        3 minutes ago       827 MB     # <==== that's it!
+<none>              <none>              e3be26e603f0        5 minutes ago       824 MB
+centos              7.4                 0cd976dc0a98        10 months ago       195 MB
+
+
+== How to copy already built binaries
+
+id=$(docker create checkit-tiff)
+
+docker cp $id:/tmp/checkit_tiff_current.tgz ./
+docker cp $id:/tmp/checkit_tiff_upcoming.tgz ./
+
+docker rm -v $id
+