Merge pull request #27 from mihaiconstantin/docs/license

Add `CC BY 4.0` license to documentation content

NEWS.md

@@ -1,6 +1,8 @@
 # Development
 
 ## Added
+- Add `CC BY 4.0` license for package documentation, vignettes, and website
+  content.
 - Add code coverage `GitHub` workflow via
   [`codecov`](https://codecov.io/gh/mihaiconstantin/parabar) and badge in
   `README`.

README.md

@@ -491,5 +491,6 @@ Check out the UML diagram below for a quick overview of the package design.
   [issue](https://github.com/mihaiconstantin/parabar/issues) on `GitHub`.
 
 ## License
-The code in this repository is licensed under the [MIT
-license](https://opensource.org/license/mit/).
+- The package source code in this repository is licensed under the [MIT
+  license](https://opensource.org/license/mit/).
+- <p xmlns:cc="http://creativecommons.org/ns#" xmlns:dct="http://purl.org/dc/terms/"><a property="dct:title" rel="cc:attributionURL" href="https://parabar.mihaiconstantin.com">The documentation, vignettes, and other website materials</a> by <a rel="cc:attributionURL dct:creator" property="cc:attributionName" href="https://mihaiconstantin.com">Mihai Constantin</a> are licensed under <a href="http://creativecommons.org/licenses/by/4.0/?ref=chooser-v1" target="_blank" rel="license noopener noreferrer" style="display:inline-block;">CC BY 4.0<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;" src="https://mirrors.creativecommons.org/presskit/icons/cc.svg?ref=chooser-v1"><img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;" src="https://mirrors.creativecommons.org/presskit/icons/by.svg?ref=chooser-v1"></a>.</p>