docs: remove implementation details from cookies options

closes #128

README.md

@@ -76,8 +76,8 @@ The options can also contain any of the following (for the full list, see
   - `secure`: a boolean indicating whether the cookie is only to be sent over HTTPS (`false` by default for HTTP, `true` by default for HTTPS).
   - `secureProxy`: a boolean indicating whether the cookie is only to be sent over HTTPS (use this if you handle SSL not in your node process).
   - `httpOnly`: a boolean indicating whether the cookie is only to be sent over HTTP(S), and not made available to client JavaScript (`true` by default).
-  - `signed`: a boolean indicating whether the cookie is to be signed (`true` by default). If this is true, another cookie of the same name with the `.sig` suffix appended will also be sent, with a 27-byte url-safe base64 SHA1 value representing the hash of _cookie-name_=_cookie-value_ against the first [Keygrip](https://github.com/expressjs/keygrip) key. This signature key is used to detect tampering the next time a cookie is received.
-  - `overwrite`: a boolean indicating whether to overwrite previously set cookies of the same name (`true` by default). If this is true, all cookies set during the same request with the same name (regardless of path or domain) are filtered out of the Set-Cookie header when setting this cookie.
+  - `signed`: a boolean indicating whether the cookie is to be signed (`true` by default).
+  - `overwrite`: a boolean indicating whether to overwrite previously set cookies of the same name (`true` by default).
 
 ### req.session