install page: add new "Build from source" page

Signed-off-by: Julia Evans <[email protected]>

Author: jvns

content/install/source.html

@@ -0,0 +1,20 @@
+---
+section: "install"
+title: "Git - Build from Source"
+---
+
+<div id="main">
+  {{< install-header "source" >}}
+
+    <div class="install-content">
+
+<p>If you prefer to build from source, you can find tarballs
+  <a href="https://www.kernel.org/pub/software/scm/git/">on kernel.org</a>.
+  The latest version is
+  <a href="https://www.kernel.org/pub/software/scm/git/git-{{< site-param "latest_version" >}}.tar.gz">{{< site-param "latest_version" >}}</a>.
+</p>
+<p>There's also an official <a href="https://github.com/git/git">GitHub mirror</a>.</p>
+
+</div>
+</div>
+</div>