transactional-update-2.11-bp150.2.6.1

- Use noun phrase in summary.

- Update to version 2.11
  - Update man page to explain new /etc overlay handling
  - Add special handling for migrating away from old overlay directory
  - Read default update method for systemd service from config file
- Add package "transactional-update-zypp-config" to prevent accidental
  transactional-update uninstallation on transactional systems
  (boo#1111319)
- Use "up" for systemd service on non-rolling release distributions
  (boo#1111321)

- Update to version 2.10
  - Introduce /etc overlays
  - Each root file system snapshot now has a dedicated /etc overlay in
    /var/lib/snapshots/<snapshot number>/etc
  - Changes in older snapshots will be visible in newer snapshots (if
    the file hasn't been changed in both snapshots), but not the other
    way around; this makes it possible to roll back to a previous
    snapshot even if the configuration is broken
  - The /etc state of the oldest active snapshot will be synchronized
    into the new snapshot to prevent ever growing overlays
  - Removed creation of /etc backup snapshots
  - Removed complex overlayfs cleanup handling during dracut early boot;
    only thing left is to output a warning if files have been changed
    in old and new overlay after snapshot creation
  - Unused overlays will be removed during "cleanup" operation
  - Add compatibility with snapper >= 0.7.0
  - Correctly detect BTRFS ID when using multiple snapper configurations
  - Fix disappearing prompt in "shell" command when application was updated
  - Prevent accidental rollback on fast reboots (boo#1111786)
  - Use zypper attribute packages-to-change if available (boo#1105992 &
    boo#1097619)
  - Add kexec as reboot alternative
  - Added explicit --with-doc / --without-doc build configure opttions for
    enforcing or excluding documentation build
  - Removed precompiled documentation (boo#1088676)
  - Added more dependency checks to configure script
  - Small improvements to documentation
  - Restored compatibility with older rsync versions not supporting the -x
    filter
  - Small bugfixes for cleanup in error situations
  - Fix possible incorrect detection of snapshots numbers during cleanup
  - Mention parent in snapshot description
- Add dependencies for documentation build (boo#1088676)