Sneaky update to 0.2.0 spec to link unstable

This doesn't count as a spec release, right??

specification/client_server_api.rst

@@ -45,7 +45,7 @@ Other versions of this specification
 
 The following other versions are also available, in reverse chronological order:
 
-- `HEAD <https://matrix.org/speculator/spec/head/client_server.html>`_: Includes all changes since the latest versioned release.
+- `HEAD <https://matrix.org/docs/spec/client_server/unstable.html>`_: Includes all changes since the latest versioned release.
 - `r0.1.0 <https://matrix.org/docs/spec/client_server/r0.1.0.html>`_
 - `r0.0.1 <https://matrix.org/docs/spec/r0.0.1/client_server.html>`_
 - `r0.0.0 <https://matrix.org/docs/spec/r0.0.0/client_server.html>`_