doc: fix typo in tls.md · nodejs/node@ddee71a

Original file line number	Diff line number	Diff line change
`@@ -467,7 +467,7 @@ added: v0.11.4`
`467`	`467`
`468`	`468`	* `socket` {net.Socket} An instance of [`net.Socket`][]
`469`	`469`	* `options` {Object}
`470`		-* `isServer`: The SSL/TLS protocol is asymetrical, TLSSockets must know if
	`470`	+* `isServer`: The SSL/TLS protocol is asymmetrical, TLSSockets must know if
`471`	`471`	they are to behave as a server or a client. If `true` the TLS socket will be
`472`	`472`	instantiated as a server. Defaults to `false`.
`473`	`473`	* `server` {net.Server} An optional [`net.Server`][] instance.