Update readme

README.md

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-0publish
---------
+# 0publish
 
-The old tool for publishing 0install feeds. New users should use [0template][] and [0repo][] instead.
+0publish makes creating and modifying Zero Install feed files easier.
+It can create a new commented template for you or edit an existing one.
 
-See <http://0install.net/0publish.html> for documentation.
+Various editing operations are available, the most basic being to let you
+edit it in your preferred text editor. It automatically removes the
+signature when loading an interface and creates a new one when writing it
+back out. It will also validate the new version before saving it.
 
-[0template]: http://0install.net/0template.html
-[0repo]: http://0install.net/0repo.html
+**[Documentation and download instructions](https://docs.0install.net/tools/0publish/)**
+
+## Other versions
+
+See also the [.NET version](https://github.com/0install/0publish-dotnet) of this program, for use on Windows.