docs: Capitalize GitHub properly.

README.md

@@ -42,7 +42,7 @@ possible bugs.  Zulip also has a [blog](https://blog.zulip.org/).
 
 Last but not least, we use [GitHub](https://github.com/zulip/zulip) to
 track Zulip-related issues (and store our code, of course).
-Anybody with a Github account should be able to create Issues there
+Anybody with a GitHub account should be able to create Issues there
 pertaining to bugs or enhancement requests.  We also use Pull
 Requests as our primary mechanism to receive code contributions.
 

templates/zerver/features.html

@@ -125,7 +125,7 @@
         <h4>{{ _("Integrations") }}</h4>
         <p>{% trans %}Get alerts and updates from your favorite services with
         off-the-shelf <a href="{{ server_uri }}/integrations">integrations</a> for
-        Trac, Nagios, Github, Jenkins, and more.{% endtrans %}</p>
+        Trac, Nagios, GitHub, Jenkins, and more.{% endtrans %}</p>
       </div>
       <div class="feature-block">
         <i class="icon-vector-sitemap icon-vector-3x feature-icon"></i>

templates/zerver/integrations.html

@@ -867,7 +867,7 @@
       notifications to a specified set of branches.</p>
 
       <p>Further configuration is possible. By default, commits traffic (pushes, commit comments),
-      Github issues traffic, and pull requests are enabled. You can exclude certain types of traffic
+      GitHub issues traffic, and pull requests are enabled. You can exclude certain types of traffic
       via the checkboxes. If you want commit traffic, issue traffic, and pull requests to go to
       different places, you can use the <b>Commit Stream</b> and <b>Issue Stream</b> overrides;
       otherwise, it is safe to leave these fields blank and just have it default to the <b>Stream</b>