Updated README to describe hos to install the plugin

Change-Id: Ic0df840e2b50dc43c50661fe8ac1994c370d63e5

README.md

diff --git a/README.md b/README.md
index 109348a..6102a91 100644
--- a/README.md
+++ b/README.md
@@ -10,4 +10,46 @@
 ## License
 The
 [Eclipe Public License](https://protobuf-dt.googlesource.com/protobuf/+/master/com.google.eclipse.protobuf.feature/epl-v10.html)
-can be found in com.eclipse.protobuf.feature.
\ No newline at end of file
+can be found in com.eclipse.protobuf.feature.
+
+## Installing protobuf-dt
+The update site for protobuf-dt is
+http://google.github.io/protobuf-dt/updates/latest/.
+
+### Install using Eclipse Install tool
+Navigate to "Help" > "Install New Software...".
+
+Click **Add...**.
+
+Enter _Protobuf Editor_ into the "Name:" field.
+
+Paste _http://google.github.io/protobuf-dt/updates/latest/_
+into the "Location:" field.
+
+Click **OK**.
+
+From the dropdown labeled "Work with:" select the repository you just added.
+
+Make sure that "Group items by category" is deselected.
+
+"Google Inc." should be listed in the repository explorer window.
+
+Select the checkbox next to "Google Inc.".
+
+Click **Next**.
+
+Click **Next** again on the "Item Details" page.
+
+Accept the terms of the license agreement and click **Finish**.
+
+### Install using the Eclipse Marketplace
+Navigate to "Help" > "Eclipse Marketplace...".
+
+Search for _protobuf-dt_.
+
+"protobuf-dt" should be listed in the search window.
+
+Click "Install".
+
+Accept the terms of the license agreement and click **Finish**.
+