Add header anchors to common device page sections.

Change-Id: I5b9a88a3c973a95725095e825db9fa8cb2b342ae
diff --git a/_includes/twrpinstall.html b/_includes/twrpinstall.html
index 2ed3389..fd36ff2 100644
--- a/_includes/twrpinstall.html
+++ b/_includes/twrpinstall.html
@@ -1,3 +1,3 @@
-<div class='page-heading'>TWRP Install (Requires TWRP 2.8.4 or higher already installed):</div>
+<div class='page-heading' id='twrp-install'>TWRP Install (Requires TWRP 2.8.4 or higher already installed):</div>
 <hr />
 <p class="text">Download the latest TWRP image file (.img) from the download link and boot TWRP. Go to install and find and select the Images... button. Browse to the image that you downloaded and select it. Choose recovery and swipe to flash.</p>