Point to Open Source Friday

- Add Open Source Friday to the "How To Contribute" list and tweak the
  wording to suggest that it's more than just discovery (this applies to
  other projects in that list too)
- On Fridays show a link to Open Source Friday on the index page

Author: MikeMcQuaid

_articles/how-to-contribute.md

@@ -210,9 +210,10 @@ You might scan a README and find a broken link or a typo. Or you're a new user a
 
 > [28% of casual contributions](http://www.igor.pro.br/publica/papers/saner2016.pdf) to open source are documentation, such as a typo fix, reformatting, or writing a translation.
 
-You can also use one of the following resources to help you discover new projects:
+You can also use one of the following resources to help you discover and contribute to new projects:
 
 * [GitHub Explore](https://github.com/explore/)
+* [Open Source Friday](https://opensourcefriday.com)
 * [First Timers Only](http://www.firsttimersonly.com/)
 * [Your First PR](https://yourfirstpr.github.io/)
 * [CodeTriage](https://www.codetriage.com/)

assets/js/index.js

@@ -15,3 +15,11 @@
 
   $(selector).wrapInner('<span/>');
 })();
+
+(function() {
+  var FRIDAY = 5;
+  var today = new Date();
+  if (FRIDAY == today.getDay()) {
+    $("#opensourcefriday").show();
+  }
+})();

index.html

@@ -25,6 +25,10 @@ <h1 class="alt-h1">Open Source Guides</h1>
       <p class="alt-lead text-gray mb-md-5 col-md-8 mx-auto">
         Open source software is made by people just like you. Learn how to launch and grow your project.
       </p>
+      <p class="alt-lead" id="opensourcefriday" style="display:none">
+        It's Friday! Invest a few hours contributing to the software you use and love:
+        <a href='https://opensourcefriday.com'>opensourcefriday.com</a>
+      </p>
     </div>
   </header>