chore(index): GitHubのリポジトリやTwitterへのリンクを追加した

index.adoc

@@ -11,6 +11,24 @@
 
 ifeval::["{backend}" == "html5"]
 
+=====
+icon:twitter[2x, link=https://twitter.com/search?f=realtime&q=%23SteinsGit] この書籍のハッシュタグは https://twitter.com/search?f=realtime&q=%23SteinsGit[#SteinsGit] です。
+=====
+
+=====
+icon:github[2x, link=https://github.com/o2project/steins-git] リポジトリは https://github.com/o2project/steins-git[o2project/steins-git] です。
+=====
+
+++++
+<iframe src="http://ghbtns.com/github-btn.html?user=o2project&repo=steins-git&type=watch&count=true"
+  allowtransparency="true" frameborder="0" scrolling="0" width="100" height="20"></iframe>
+
+<a href="https://twitter.com/share" class="twitter-share-button" data-url="http://o2project.github.io/steins-git/" data-lang="ja" data-hashtags="SteinsGit">ツイート</a>
+<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?'http':'https';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+'://platform.twitter.com/widgets.js';fjs.parentNode.insertBefore(js,fjs);}}(document, 'script', 'twitter-wjs');</script>
+++++
+
+---
+
 [IMPORTANT]
 =====
 *この書籍はSteins;Gateのネタバレを含んでいます。*
@@ -28,9 +46,11 @@ ifeval::["{backend}" == "html5"]
 
 [IMPORTANT]
 =====
-この書籍の進行状況は https://github.com/o2project/steins-git/issues?state=open[Issues · o2project/steins-git] や以下から確認できます。
+*この書籍の進行状況は https://github.com/o2project/steins-git/issues?state=open[Issues · o2project/steins-git] や以下から確認できます。*
 =====
 
+---
+
 endif::[]
 
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