Merge pull request #179 from risseraka/master

fix typo

Author: jfromaniello

Diff for: README.md

@@ -27,8 +27,8 @@ encoded private key for RSA and ECDSA.
 `options`:
 
 * `algorithm` (default: `HS256`)
-* `expiresIn`: expressed in seconds or an string describing a time span [rauchg/ms](https://github.com/rauchg/ms.js). Eg: `60`, `"2 days"`, `"10h"`, `"7d"`
-* `notBefore`: expressed in seconds or an string describing a time span [rauchg/ms](https://github.com/rauchg/ms.js). Eg: `60`, `"2 days"`, `"10h"`, `"7d"`
+* `expiresIn`: expressed in seconds or a string describing a time span [rauchg/ms](https://github.com/rauchg/ms.js). Eg: `60`, `"2 days"`, `"10h"`, `"7d"`
+* `notBefore`: expressed in seconds or a string describing a time span [rauchg/ms](https://github.com/rauchg/ms.js). Eg: `60`, `"2 days"`, `"10h"`, `"7d"`
 * `audience`
 * `subject`
 * `issuer`