Augment firmware flashing guide with images (#329)

* Augment firmware flashing guide with images

* minor language touchups

* Include PUREBOOT screen screenshot

site/source/user-manual/flashing/flashing-firmware.rst

@@ -15,18 +15,42 @@ The source code can be viewed on Purism's `firmware git repo <https://source.pur
 
     .. note:: You'll need a monitor and keyboard plugged into your Librem Mini for this operation
 
-#. Turn on the Librem Mini while pressing the ``ESC`` key on the keyboard repeatedly, until you see the PureBoot Basic Boot Menu appear.  Continue to the main menu.
+#. Turn on the Librem Mini while pressing the ``ESC`` key on the keyboard repeatedly while you see this screen:
 
-#. Select "Options -->."
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step0-pureboot_screen.jpg
+        :width: 30%
 
-#. Select "Flash/Update the BIOS".
+#. The PureBoot Basic Boot Menu screen will appear.  Select "Options -->"
 
-#. Select "Flash the firmware with a new ROM, erase settings."
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step1-pureboot_basic_boot_menu-options.jpg
+        :width: 30%
 
-#. The system will ask if you want to proceed to flash the BIOS, select "Yes."
+#. Select "Flash/Update the BIOS"
 
-#. Choose the file that we downloaded earlier: ``pureboot-librem_mini_v2-basic_usb_autoboot.rom``.
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step2-flash_update_the_bios.jpg
+        :width: 30%
 
-#. Confirm you want to proceed by selecting "Yes."
+#. Select "Flash the firmware with a new ROM, erase settings"
 
-#. The BIOS will be reflashed with the custom firmware.  This may take a few minutes.  When complete, remove the firmware USB (and insert your embassyOS USB if you are ready to install), then select "OK" to complete the process.
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step3-flash_firmware_with_new_rom.jpg
+        :width: 30%
+
+#. The system will ask if you want to proceed flashing the BIOS with a new ROM, select "Yes"
+
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step4-proceed_yes.jpg
+        :width: 30%
+
+#. Choose the file that we downloaded and copied to the USB stick earlier: ``pureboot-librem_mini_v2-basic_usb_autoboot.rom``
+
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step5-select_your_file.jpg
+        :width: 30%
+
+#. Confirm you want to proceed with the flash by selecting "Yes"
+
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step6-proceed_yes.jpg
+        :width: 30%
+
+#. The BIOS will be reflashed with the new firmware.  This may take a few minutes.  When complete, remove the firmware USB (and insert your embassyOS USB if you are ready to install), then select "OK" to complete the process.
+
+    .. figure:: /_static/images/flashing/flash_firmware-pro-step7-flashed_successfully.jpg
+        :width: 30%