Update readme with History and Download sections. Include information…

… about location in the mediawiki repo

README

@@ -10,6 +10,16 @@ report bugs and problems, visit the GitHub project page:
 
     http://www.github.com/Whiteknight/mediawiki-embedvideo
 
+=== History ===
+
+The original version of EmbedVideo was created by Jim R. Wilson. That version
+was later forked by Mohammed Derakhshani as the EmbedVideoPlus extension. In
+early 2010 Andrew Whitworth took over active maintenance of both extensions
+and merged them together as "EmbedVideo".
+
+The newer versions of EmbedVideo are intended to be fully backwards-compatible
+with both older EmbedVideo and EmbedVideoPlus extensions.
+
 == License ==
 
 EmbedVideo is released under the MIT license
@@ -20,6 +30,30 @@ See LICENSE for more details
 
 == Installation ==
 
+=== Download ===
+
+There are three places to download the EmbedVideo extension. The first is
+directly from its GitHub project page, where active development takes place.
+If you have git, you can use this incantation to check out a read-only copy
+of the extension source:
+
+    git clone git://github.com/Whiteknight/mediawiki-embedvideo.git
+
+Downloadable archive packages for numbered releases will also be available
+from the github project page.
+
+You can also download a snapshot version, typically representing a beta test
+version or a final release from the mediawiki svn repository:
+
+    svn co http://svn.wikimedia.org/svnroot/mediawiki/trunk/extensions/EmbedVideo
+
+Versions of EmbedVideo targetted towards tagged releases of mediawiki may also
+be available in the mediawiki svn repository under the specific tagged
+release.
+
+=== Installation Instructions ===
+
+# Download the contents of the extension, as outlined above.
 # Create an EmbedVideo folder in the extensions/ folder of your MediaWiki
 installation.
 # Copy the contents of this distribution into that folder