remove design doc (#647)

Author: jcstein

README.md

@@ -2,8 +2,6 @@
 
 ABCI-client implementation for Optimistic Rollups.
 
-Design document: <https://docs.google.com/document/d/12gZow_JTJjRrmaD2mNTmYniLhyxVLSyDd7Fbxo5UnA8/edit?usp=sharing>
-
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