Adding release notes to docs home

This is a temporary solution until we have a dedicated release notes page with automated content.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Be more explicit about volume removal

Signed-off-by: Peter Salvatore <peter@psftw.com>
docker save: ability to save multiple images

Now from a single invocation of `docker save`, you can specify multiple
images to include in the output tar, or even just multiple tags of a
particular image/repo.

```
> docker save -o bundle.tar busybox ubuntu:lucid ubuntu:saucy fedora:latest
> tar tf ./bundle.tar | wc -l
42
> tar xOf ./bundle.tar repositories
{"busybox":{"latest":"2d8e5b282c81244037eb15b2068e1c46319c1a42b80493acb128da24b2090739"},"fedora":{"latest":"58394af373423902a1b97f209a31e3777932d9321ef10e64feaaa7b4df609cf9"},"ubuntu":{"lucid":"9cc9ea5ea540116b89e41898dd30858107c1175260fb7ff50322b34704092232","saucy":"9f676bd305a43a931a8d98b13e5840ffbebcd908370765373315926024c7c35e"}}
```

Further, this fixes the bug where the `repositories` file is not created
when saving a specific tag of an image (e.g. ubuntu:latest)

document multi-image save and updated API docs

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Fixed typos based on feedback.

Docker-DCO-1.1-Signed-off-by: Fred Lifton <fred.lifton@docker.com> (github: fredlf)
Merge pull request #7769 from fredlf/1.2.0_release-notes

Adding release notes to docs home
Give the <strong> tag some CSS (the .content-body resets it)

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #7786 from psftw/volume_removal

Be more explicit about volume lifecycle
Merge pull request #7789 from SvenDowideit/add-css-for-strong-tag

Give the <strong> tag some CSS (the .content-body resets it)
save many: adding an integration-cli test

Signed-off-by: Vincent Batts <vbatts@redhat.com>
Merge pull request #5518 from vbatts/vbatts-save_many

docker save: ability to save multiple images