updated installer's doc for airgapped procedures

docs/getting-started/installing/from-gui/usage.en.md

@@ -118,7 +118,12 @@ Once you choose the device and version, it enables the "flash device" button. It
 
     * Unzip the correct firmware;
 
-    * The flash itself;
+    * Flash:
+
+        * The flash itself via USB;
+
+        * Air-gapped update via microSD;
+
 
 * For beta releases:
 
@@ -153,8 +158,6 @@ Krux-installer download can download four assets for official releases or one fo
 
 * A `kfpkg` file containing the specific firmware for choosen device;
 
-<img width="640" src="/krux/img/krux-installer/download_beta.png" alt="KruxInstaller downloading kboot.kfpkg" />
-
 #### Verification
 
 * Integrity verification compares the computed hash of `zip` against thei provided `zip.sha256.txt`;
@@ -167,11 +170,13 @@ the `zip.sig` and `selfcustody.pem`.
 
 #### Unzip
 
-Now you will be able to select if you do a flash process or need to do an airgap process (soon):
+Now you will be able to select if you do a flash process or need to do an airgap process:
 
 <img width="640" src="/krux/img/krux-installer/unzip.png" alt="KruxInstaller unzip" />
 
-#### Flash
+Click on [Flash with](#flash) to install via USB or [Air-gapped update with](#air-gapped-update-with) to perform upgrades via a microSD card.
+
+#### Flash with
 
 When flash starts, it will warn you to **not disconnect the device until the process is complete**.
 You'll be able to see the flash progress:
@@ -188,6 +193,30 @@ As well a done icon:
 flash-krux-logo.en.txt
 ----8<----
 
+#### Air-gapped update with
+
+Once you've installed the initial firmware on your device via USB, you can perform upgrades via microSD card to keep the device airgapped.
+
+<img width="640" src="/krux/img/krux-installer/unzip.png" alt="KruxInstaller unzip" />
+> ⚠️ Click on "Air-gapped update with"
+
+Once the `firmware.bin` and `firmware.bin.sig` are extracted, you'll see a warning message.
+
+<img width="640" src="/krux/img/krux-installer/warn_airgap.png" alt="KruxInstaller warn airgap" />
+
+Insert the microSD and click "Proceed" to installer detect the microSD card. 
+
+<img width="640" src="/krux/img/krux-installer/list_drivers.png" alt="KruxInstaller warn airgap" />
+> ⚠️ If you one microSD, the screen will be turned on a big button. If you have more removable drives, both microSD and drives will be listed
+
+Click on desired removable drive to copy both `firmware.bin` and `firmware.bin.sig`. The first is the krux firmware itself and the second
+is a file that assert both firmware's integrity and authenticity. 
+
+Now you can compare the firmware's hash computed by installer with  the firmware's hash computed by the device. 
+
+<img width="640" src="/krux/img/krux-installer/airgap_done.png" alt="KruxInstaller warn airgap" />
+> ⚠️ Once files are copied, remove the microSD from computer, connect to device and compare the hashes
+
 ### Wipe device
 
 This is two step process:

mkdocs.yml

@@ -52,12 +52,12 @@ docs_dir: docs
 site_dir: public
 extra:
   latest_krux: krux-v24.09.1
-  latest_installer: v0.0.20-alpha-3
-  latest_installer_rpm: krux-installer-0.0.20_alpha_3-1.x86_64.rpm
-  latest_installer_deb: krux-installer_0.0.20-alpha-3_amd64.deb
-  latest_installer_win: krux-installer_v0.0.20-alpha-3.Setup.exe
-  latest_installer_mac_arm: krux-installer_0.0.20-alpha-3_arm64.dmg
-  latest_installer_mac_intel: krux-installer_0.0.20-alpha-3_x86_64.dmg
+  latest_installer: v0.0.20-beta
+  latest_installer_rpm: krux-installer-0.0.20_beta-1.x86_64.rpm
+  latest_installer_deb: krux-installer_0.0.20-beta_amd64.deb
+  latest_installer_win: krux-installer_v0.0.20-beta.Setup.exe
+  latest_installer_mac_arm: krux-installer_0.0.20-beta_arm64.dmg
+  latest_installer_mac_intel: krux-installer_0.0.20-beta_x86_64.dmg
   social:
     - icon: fontawesome/solid/bullhorn
       link: https://bitcointalk.org/index.php?topic=5489022.0