Add |wallet fees| subcommand for easy viewing of the current cluster fees (#4596)

book/src/wallet.md

@@ -284,6 +284,18 @@ ARGS:
     <PATH>    /path/to/program.o
 ```
 
+```manpage
+solana-wallet-fees
+Display current cluster fees
+
+USAGE:
+    solana-wallet fees
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+```
+
 ```manpage
 solana-wallet-get-transaction-count
 Get current transaction count