clarify that phenix 1.21 is supported

docs/quickstart.md

@@ -30,7 +30,7 @@ Though `matchmaps` is a python package, it relies on two pieces of external soft
 
 ```{eval-rst}
 .. note::
-    Please note that phenix 1.21 is **not** supported at this time. I hope to update `matchmaps` to support this in the near future. In the meantime, make sure you're using phenix 1.20 or earlier, and everything should work fine. As of `matchmaps 0.6.3`, an error should be thrown if you're using phenix 1.21 reminding you to downgrade.
+    As of `matchmaps 0.6.4`, support for phenix version 1.21 has been added. If you are using phenix 1.21, make sure that you have updated `matchmaps` to the most recent version, and everything should work fine. phenix 1.20 is also supported by current and previous `matchmaps` versions.
 ```
 When actually using `matchmaps` in the command-line, you'll need to have both ccp4 and phenix active. Doing that will look something like:
 ```bash