Fix the example tx in README.md (FuelLabs#1543)

I wonder if we should add an automatic test that makes sure the example
here actually works.

README.md

@@ -188,7 +188,7 @@ RET(RegId::ONE),
 
 ```console
 $ cargo run --bin fuel-core-client -- transaction submit \
-"{\"Script\":{\"gas_price\":0,\"gas_limit\":1000000,\"maturity\":0,\"script\":[80,64,0,202,80,68,0,186,51,65,16,0,36,4,0,0],\"script_data\":[],\"inputs\":[
+"{\"Script\":{\"script_gas_limit\":1000000,\"policies\":{\"bits\":\"GasPrice\",\"values\":[0,0,0,0]},\"maturity\":0,\"script\":[80,64,0,202,80,68,0,186,51,65,16,0,36,4,0,0],\"script_data\":[],\"inputs\":[
 {
   \"CoinSigned\": {
     \"utxo_id\": {
@@ -210,70 +210,7 @@ $ cargo run --bin fuel-core-client -- transaction submit \
   }
 }],\"outputs\":[],\"witnesses\":[{
   \"data\": [
-    150,
-    31,
-    98,
-    51,
-    6,
-    239,
-    255,
-    243,
-    45,
-    35,
-    182,
-    26,
-    129,
-    152,
-    46,
-    95,
-    45,
-    211,
-    114,
-    58,
-    51,
-    64,
-    129,
-    194,
-    97,
-    14,
-    181,
-    70,
-    190,
-    37,
-    106,
-    223,
-    170,
-    174,
-    221,
-    230,
-    87,
-    239,
-    67,
-    224,
-    100,
-    137,
-    25,
-    249,
-    193,
-    14,
-    184,
-    195,
-    15,
-    85,
-    156,
-    82,
-    91,
-    78,
-    91,
-    80,
-    126,
-    168,
-    215,
-    170,
-    139,
-    48,
-    19,
-    5
+    150,31,98,51,6,239,255,243,45,35,182,26,129,152,46,95,45,211,114,58,51,64,129,194,97,14,181,70,190,37,106,223,170,174,221,230,87,239,67,224,100,137,25,249,193,14,184,195,15,85,156,82,91,78,91,80,126,168,215,170,139,48,19,5
   ]
 }],\"receipts_root\":\"0x6114142d12e0f58cfb8c72c270cd0535944fb1ba763dce83c17e882c482224a2\"}}"
 ```