docs: Update README.md for rel 2.0.2.

README.md

@@ -46,7 +46,7 @@ changes may be written to a config file in a platform-specific location:
   this repository:
 
   ```sh
-  $ go install decred.org/[email protected].0
+  $ go install decred.org/[email protected].2
   ```
 
   Using `@master` instead will perform a release build using the latest code