docs(cosmos/x/vstorage): Add README section for CLI

golang/cosmos/x/vstorage/README.md

@@ -34,6 +34,28 @@ This is used by the SwingSet "bridge".
   * method "size", args path (returns the count of children)
 * StreamCell-oriented
   * method "append", args [[path, value?], ...]
+
+## CLI
+
+A blockchain node may be interrogated by RPC using `agd [--node $url] query vstorage $command` via [client/cli](./client/cli/query.go).
+* `children [--height $blockHeight] [-o {text,json}] [$path]`
+* `data [--height $blockHeight] [-o {text,json}] $path`
+
+Examples:
+```sh
+$ agd --node https://main.rpc.agoric.net:443/ query vstorage children published.reserve
+children:
+- governance
+- metrics
+pagination: null
+
+$ agd --node https://main.rpc.agoric.net:443/ query vstorage children -o json published.reserve
+{"children":["governance","metrics"],"pagination":null}
+
+$ agd --node https://main.rpc.agoric.net:443/ query vstorage data published.reserve.metrics
+value: '{"blockHeight":"11030240","values":["{\"body\":\"#{\\\"allocations\\\":{\\\"Fee\\\":{\\\"brand\\\":\\\"$0.Alleged:
+  IST brand\\\",\\\"value\\\":\\\"+20053582387\\\"}},\\\"shortfallBalance\\\":{\\\"brand\\\":\\\"$0\\\",\\\"value\\\":\\\"+0\\\"},\\\"totalFeeBurned\\\":{\\\"brand\\\":\\\"$0\\\",\\\"value\\\":\\\"+0\\\"},\\\"totalFeeMinted\\\":{\\\"brand\\\":\\\"$0\\\",\\\"value\\\":\\\"+0\\\"}}\",\"slots\":[\"board0257\"]}"]}'
+```
 
 ## External protobuf interface