feat(cli): change orderbook default precision

This commit changes orderbook's default precision from 5 to 8 decimals
in order to prevent confusing scenarios where it was possible to see
"the same" price with for buy and sell orders using `xucli orderbook`.

In reality the last 3 digits were different, causing the matching engine
not to trigger a swap.

Author: Karl Ranna

Diff for: lib/cli/commands/orderbook.ts

@@ -152,7 +152,7 @@ export const builder = {
   precision: {
     describe: 'the number of digits following the decimal point',
     type: 'number',
-    default: 5,
+    default: 8,
   },
 };