Centos project does not support custom kernels - see #9696

Signed-off-by: Sven Dowideit <SvenDowideit@docker.com>

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)

docs/sources/installation/centos.md

@@ -27,6 +27,13 @@ simply run the following command.
 
     $ sudo yum install docker
 
+## Kernel support
+
+Currently the CentOS project will only support Docker via the EPEL package when
+running on kernels shipped by the distribution. There are things like namespace
+changes which will cause issues if one decides to step outside that box and run
+non-distro kernel packages.
+
 ### Manual installation of latest version
 
 While using a package is the recommended way of installing Docker,

docs/sources/installation/rhel.md

@@ -40,6 +40,13 @@ You will need [RHEL
 a RHEL 6 kernel version 2.6.32-431 or higher as this has specific kernel
 fixes to allow Docker to work.
 
+## Kernel support
+
+RHEL will only support Docker via the *extras* channel or EPEL package when
+running on kernels shipped by the distribution. There are things like namespace
+changes which will cause issues if one decides to step outside that box and run
+non-distro kernel packages.
+
 ## Installation
 
 Firstly, you need to install the EPEL repository. Please follow the