Readme : fix broken link to docs (prebid#12031)

* Readme : fix broken link to docs

* Update README.md

* Update README.md

---------

Co-authored-by: Patrick McCann <patmmccann@gmail.com>

README.md

@@ -1,14 +1,14 @@
 [![Build Status](https://circleci.com/gh/prebid/Prebid.js.svg?style=svg)](https://circleci.com/gh/prebid/Prebid.js)
-[![Percentage of issues still open](http://isitmaintained.com/badge/open/prebid/Prebid.js.svg)](http://isitmaintained.com/project/prebid/Prebid.js "Percentage of issues still open")
+[![Percentage of issues still open](http://isitmaintained.com/badge/open/prebid/Prebid.js.svg)](https://isitmaintained.com/project/prebid/Prebid.js "Percentage of issues still open")
 [![Coverage Status](https://coveralls.io/repos/github/prebid/Prebid.js/badge.svg)](https://coveralls.io/github/prebid/Prebid.js)
 
 # Prebid.js
 
 > A free and open source library for publishers to quickly implement header bidding.
 
 This README is for developers who want to contribute to Prebid.js.
-Additional documentation can be found at [the Prebid homepage](http://prebid.org).
-Working examples can be found in [the developer docs](http://prebid.org/dev-docs/getting-started.html).
+Additional documentation can be found at [the Prebid.js documentation homepage](https://docs.prebid.org/prebid/prebidjs.html).
+Working examples can be found in [the developer docs](https://prebid.org/dev-docs/getting-started.html).
 
 Prebid.js is open source software that is offered for free as a convenience. While it is designed to help companies address legal requirements associated with header bidding, we cannot and do not warrant that your use of Prebid.js will satisfy legal requirements. You are solely responsible for ensuring that your use of Prebid.js complies with all applicable laws.  We strongly encourage you to obtain legal advice when using Prebid.js to ensure your implementation complies with all laws where you operate.
 
@@ -374,7 +374,7 @@ The results will be in
 
 *Note*: Starting in June 2016, all pull requests to Prebid.js need to include tests with greater than 80% code coverage before they can be merged.  For more information, see [#421](https://github.com/prebid/Prebid.js/issues/421).
 
-For instructions on writing tests for Prebid.js, see [Testing Prebid.js](http://prebid.org/dev-docs/testing-prebid.html).
+For instructions on writing tests for Prebid.js, see [Testing Prebid.js](https://prebid.org/dev-docs/testing-prebid.html).
 
 ### Supported Browsers