engine: remove some mentions of old Ubuntu and Engine versions

These were notes about distro versions that have been EOL for a long
time, and an old version of docker engine that's EOL as well.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

engine/security/apparmor.md

@@ -215,9 +215,6 @@ looks like the following:
 In the above example, you can see `profile=/usr/bin/docker`. This means the
 user has the `docker-engine` (Docker Engine Daemon) profile loaded.
 
-> **Note**: On version of Ubuntu > 14.04 this is all fine and well, but Trusty
-> users might run into some issues when trying to `docker container exec`.
-
 Look at another log line:
 
 ```

engine/security/seccomp.md

@@ -18,11 +18,6 @@ $ grep CONFIG_SECCOMP= /boot/config-$(uname -r)
 CONFIG_SECCOMP=y
 ```
 
-> **Note**: `seccomp` profiles require seccomp 2.2.1 which is not available on
-> Ubuntu 14.04, Debian Wheezy, or Debian Jessie. To use `seccomp` on these
-> distributions, you must download the [latest static Linux binaries](../install/binaries.md)
-> (rather than packages).
-
 ## Pass a profile for a container
 
 The default `seccomp` profile provides a sane default for running containers with

storage/storagedriver/zfs-driver.md

@@ -29,14 +29,6 @@ use unless you have substantial experience with ZFS on Linux.
 
 - ZFS requires one or more dedicated block devices, preferably solid-state
   drives (SSDs).
-- ZFS is only supported on Docker Engine - Community with Ubuntu 14.04 or higher, with the `zfs`
-  package (16.04 and higher) or `zfs-native` and `ubuntu-zfs` packages (14.04)
-  installed.
-  - For Ubuntu 14.04, you need to enable a supplemental package repository
-    `ppa:zfs-native/stable` before you can install the package. See
-    [https://launchpad.net/~zfs-native/+archive/ubuntu/stable](https://launchpad.net/~zfs-native/+archive/ubuntu/stable){: target="_blank" rel="noopener" class="_" }
-    for instructions.
-- ZFS is not supported on Docker EE or CS-Engine, or any other Linux platforms.
 - The `/var/lib/docker/` directory must be mounted on a ZFS-formatted
   filesystem.
 - Changing the storage driver makes any containers you have already
@@ -46,8 +38,8 @@ use unless you have substantial experience with ZFS on Linux.
 
 > **Note**
 >
-> There is no need to use `MountFlags=slave` with Docker Engine 18.09 or
+> There is no need to use `MountFlags=slave` because `dockerd` and `containerd`
-> later because `dockerd` and `containerd` are in different mount namespaces. 
+> are in different mount namespaces. 
 
 ## Configure Docker with the `zfs` storage driver