This fix fixes an error in documentation (dockerd.md). In the
example given by dockerd.md, the option `cluster-store-opts`
is assigned with an array but this option can only be assigned
as a map.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Upstream-commit: 32b234885e798650cdff70f0459175e79a294b4d
Component: engine