[lib] Add initial README.md

Signed-off-by: Julian Strobl <[email protected]>

README.md

@@ -0,0 +1,49 @@
+# Library for RPC requests to Planetmint
+
+## How to use it
+
+In the example below we use the account `addr0` for which we have the private key in our keyring.
+The only keyring backend currently supported is the test backend under `keyring-test`.
+After that we construct three messages to send `10plmnt` each to three addresses `addr1`, `addr2` and `addr3`.
+We then change the default RPC endpoint to a remote one, build and sign the transaction and eventually send this transaction via RPC.
+For debugging purposes we print the transaction that we send as JSON and also the response from the RPC endpoint.
+
+```
+package main
+
+import (
+        "fmt"
+        "log"
+
+        sdk "github.com/cosmos/cosmos-sdk/types"
+        banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
+        "github.com/planetmint/planetmint-go/lib"
+)
+
+func main() {
+        addr0 := sdk.MustAccAddressFromBech32("plmnt168z8fyyzap0nw75d4atv9ucr2ye60d57dzlzaf")
+        addr1 := sdk.MustAccAddressFromBech32("plmnt1vklujvmr9hsk9zwpquk4waecr2u5vcyjd8vgm8")
+        addr2 := sdk.MustAccAddressFromBech32("plmnt1pwquxvqmmdry4gdel4g4rz0js7jy65453h92g7")
+        addr3 := sdk.MustAccAddressFromBech32("plmnt1dyuhg8ldu3d6nvhrvzzemtc3893dys9v9lvdty")
+
+        coin := sdk.NewCoins(sdk.NewInt64Coin("plmnt", 10))
+        msg1 := banktypes.NewMsgSend(addr0, addr1, coin)
+        msg2 := banktypes.NewMsgSend(addr0, addr2, coin)
+        msg3 := banktypes.NewMsgSend(addr0, addr3, coin)
+
+        config := lib.GetConfig()
+        config.SetRPCEndpoint("https://testnet-api.rddl.io")
+
+        txBytes, txJSON, err := lib.BuildAndSignTx(addr0, msg1, msg2, msg3)
+        if err != nil {
+                log.Fatal(err)
+        }
+        fmt.Println(txJSON)
+
+        broadcastTxResponseJSON, err := lib.BroadcastTx(txBytes)
+        if err != nil {
+                log.Fatal(err)
+        }
+        fmt.Println(broadcastTxResponseJSON)
+}
+```