add hemdall install

Change-Id: I153cb95fd78eeca382814ddd28b738c65a2bb0bf
diff --git a/_samsung/samsunggalaxya12.markdown b/_samsung/samsunggalaxya12.markdown
index c0dbb7a..b131d97 100644
--- a/_samsung/samsunggalaxya12.markdown
+++ b/_samsung/samsunggalaxya12.markdown
@@ -16,4 +16,5 @@
 {% include appinstall.html %}

 {% include twrpinstall.html %}

 {% include odininstall.html %}

+{% include heimdallinstall.html %}

 {% include ddinstall.html %}
\ No newline at end of file