feat: update ledger instructions (#6673)

Description
---
Updated the ledger wallet build instructions to ensure it is still
current.

Motivation and Context
---
See above.

How Has This Been Tested?
---
- nanosplus
```
   docker run --rm -it -v ".:/app" -w /app/applications/minotari_ledger_wallet/wallet ghcr.io/ledgerhq/ledger-app-builder/ledger-app-builder cargo ledger build stax

    Finished release [optimized] target(s) in 37.50s
   text    data     bss     dec     hex filename
 129488       0   11936  141424   22870 /app/applications/minotari_ledger_wallet/wallet/target/nanosplus/release/minotari_ledger_wallet
Dumping APDU installation file to /app/applications/minotari_ledger_wallet/wallet/target/nanosplus/release/minotari_ledger_wallet.apdu
```
- stax
```
   docker run --rm -it -v ".:/app" -w /app/applications/minotari_ledger_wallet/wallet ghcr.io/ledgerhq/ledger-app-builder/ledger-app-builder cargo ledger build stax

       Finished release [optimized] target(s) in 15.47s
   text    data     bss     dec     hex filename
 177552       0   21012  198564   307a4 /app/applications/minotari_ledger_wallet/wallet/target/stax/release/minotari_ledger_wallet
Dumping APDU installation file to /app/applications/minotari_ledger_wallet/wallet/target/stax/release/minotari_ledger_wallet.apdu
``` 

What process can a PR reviewer use to test or verify this change?
---

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Breaking Changes
---

- [x] None
- [ ] Requires data directory on base node to be deleted
- [ ] Requires hard fork
- [ ] Other - Please specify

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<!-- BREAKING CHANGE: Description what the user should do, e.g. delete a
database, resync the chain -->

applications/minotari_ledger_wallet/wallet/README.md

@@ -72,13 +72,18 @@ For more information see [LedgerCTL](https://github.com/LedgerHQ/ledgerctl).
 It is recommended to build the Ledger application via the official `ledger-app-builder` Docker image, as the Docker 
 image is properly setup, supported and always kept up to date.
 
+**Note:** Before proceeding, manually delete any ledger docker images from Docker Desktop as those will not be updated 
+automatically: 
+- Select he _Images_ tab/menu item
+- Select the checkbox next to _ghcr.io/ledgerhq/ledger-app-builder/ledger-app-builder_ and then press _Delete_. 
+
 ### Option 1: Using Docker
 
 Ensure Docker Desktop is installed and running on your machine.
 
 The following command has to be run from the root of the Tari repository.  
 
-Replace ```{TARGET}``` with the appropriate value (e.g., `nanosplus`, `nanos`, etc.).
+Replace ```{TARGET}``` with the appropriate value (e.g., `nanosplus`, `stax`, etc.).
 
 Compiled resources will be found in `applications/minotari_ledger_wallet/wallet/target/{TARGET}/release`
 

applications/minotari_ledger_wallet/wallet/src/main.rs

@@ -229,7 +229,7 @@ extern "C" fn sample_main() {
             continue;
         };
 
-        let status = match handle_apdu(&mut comm, ins, &mut offset_ctx) {
+        let _status = match handle_apdu(&mut comm, ins, &mut offset_ctx) {
             Ok(()) => {
                 comm.reply_ok();
                 AppSW::Ok
@@ -239,8 +239,9 @@ extern "C" fn sample_main() {
                 sw
             },
         };
+
         #[cfg(any(target_os = "stax", target_os = "flex"))]
-        show_status_and_home_if_needed(&ins, &status, &mut offset_ctx, &mut home);
+        show_status_and_home_if_needed(&ins, &_status, &mut offset_ctx, &mut home);
     }
 }