docs:update link to guide on expressjs.com (#221)

Author: krzysdz

README.md

@@ -106,7 +106,7 @@ The options can also contain any of the following (for the full list, see
   - `partitioned`: a boolean indicating whether to partition the cookie in Chrome for the [CHIPS Update](https://developers.google.com/privacy-sandbox/3pcd/chips) (`false` by default). If this is true, Cookies from embedded sites will be partitioned and only readable from the same top level site from which it was created.
   - `priority`: a string indicating the cookie priority. This can be set to `'low'`, `'medium'`, or `'high'`.
   - `sameSite`: a boolean or string indicating whether the cookie is a "same site" cookie (`false` by default). This can be set to `'strict'`, `'lax'`, `'none'`, or `true` (which maps to `'strict'`).
-  - `secure`: a boolean indicating whether the cookie is only to be sent over HTTPS (`false` by default for HTTP, `true` by default for HTTPS). If this is set to `true` and Node.js is not directly over a TLS connection, be sure to read how to [setup Express behind proxies](https://expressjs.com/en/guide/behind-proxies.html) or the cookie may not ever set correctly.
+  - `secure`: a boolean indicating whether the cookie is only to be sent over HTTPS (`false` by default for HTTP, `true` by default for HTTPS). If this is set to `true` and Node.js is not directly over a TLS connection, be sure to read how to [setup Express behind proxies](https://expressjs.com/en/guide/behind-proxies/) or the cookie may not ever set correctly.
   - `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).
   - `overwrite`: a boolean indicating whether to overwrite previously set cookies of the same name (`true` by default).
@@ -287,4 +287,4 @@ move to an [alternative session strategy](https://github.com/expressjs/session#c
 [coveralls-url]: https://coveralls.io/r/expressjs/cookie-session?branch=master
 [npm-downloads-image]: https://img.shields.io/npm/dw/cookie-session
 [npm-url]: https://npmjs.org/package/cookie-session
-[npm-version-image]:https://img.shields.io/npm/v/cookie-session
+[npm-version-image]:https://img.shields.io/npm/v/cookie-session