config.md: fix typo of context
config.md: fix typo of context

replace `filesystemtype` with `type of filesystem`
`list of strings` should be replaced by `array of strings`

Signed-off-by: Ma Shimiao <4511f16e942ad3568742865d09c9060c1d8bebb9@cn.fujitsu.com>

opencontainers/specs,hqhq/specs,hqhq/runtime-spec,opencontainers/runtime-spec,wking/opencontainer-runtime-spec,laijs/specs,wking/opencontainer-specs