CLI JSON schema should indicate which fields are required

[david-crespo]

Without this info, the docs can't indicate which fields are required! Thanks @wfchandler for noticing.

oxide.rs/cli/src/cmd_docs.rs

Lines 22 to 33 in bcd1e9b

	/// Arg to CLI command for the JSON doc
	#[derive(Serialize, Debug, PartialEq, Eq, PartialOrd, Ord)]
	pub struct JsonArg {
	#[serde(skip_serializing_if = "Option::is_none")]
	long: Option<String>,
	#[serde(skip_serializing_if = "Option::is_none")]
	short: Option<String>,
	#[serde(skip_serializing_if = "Vec::is_empty")]
	values: Vec<String>,
	#[serde(skip_serializing_if = "Option::is_none")]
	help: Option<String>,
	}