[feat] Enable to visit repository (close #30)

Author: ftnext

source/share_buttons.rst.txt

@@ -8,6 +8,6 @@
         <!-- <a>Facebook シェア</a> -->
         <a href="https://twitter.com/share?ref_src=twsrc%5Etfw" class="twitter-share-button" data-text="Python Boot Campで全国にPythonの環を広げよう！" data-url="https://pyconjp.github.io/pycamp.landing_page/" data-hashtags="pycamp" data-lang="ja" data-dnt="true" data-show-count="false">Tweet</a><script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
         <a href="https://b.hatena.ne.jp/entry/s/pyconjp.github.io/pycamp.landing_page/" class="hatena-bookmark-button" data-hatena-bookmark-layout="vertical-normal" data-hatena-bookmark-lang="ja" title="このエントリーをはてなブックマークに追加"><img src="https://b.st-hatena.com/images/v4/public/entry-button/button-only@2x.png" alt="このエントリーをはてなブックマークに追加" width="20" height="20" style="border: none;" /></a><script type="text/javascript" src="https://b.st-hatena.com/js/bookmark_button.js" charset="utf-8" async="async"></script>
-        <span class="fab fa-github fa-xl"></span>
+        <a href="https://github.com/pyconjp/pycamp.landing_page" rel="noopener noreferrer" target="_blank"><span class="fab fa-github fa-xl" style="color: initial;"></span></a>
       </div>
     </div>