README: drop tarball unpack step

Drop the unpack archive step, as since 8f9de8a('image_types_qcom:
create image-specific subfolders'), image-specific subdirectories have
been created along with ready-to-flash artifacts, making the tarball
unpack step unnecessary.

Signed-off-by: Igor Opaniuk <[email protected]>

README.md

@@ -143,16 +143,11 @@ Make sure that ModemManager is not running, disable it if necessary.
    ```
 
 3. Plug in the USB-C cable from the host.
-4. Unpack the tarball stored in the deploy directory:
 
-   ```
-   cd build/tmp/deploy/images/qcs6490-rb3gen2-core-kit/
-   tar zxvf core-image-base-qcs6490-rb3gen2-core-kit.rootfs.qcomflash.tar.gz
-   ```
-
-5. Use the QDL tool (built in the previous section) to flash the images:
+4. Use the QDL tool (built in the previous section) to flash the images:
 
    ```
+   cd build/tmp/deploy/images/qcs6490-rb3gen2-core-kit/core-image-base-qcs6490-rb3gen2-core-kit.rootfs.qcomflash
    qdl --debug prog_firehose_ddr.elf rawprogram*.xml patch*.xml
    ```
 
@@ -165,7 +160,7 @@ Make sure that ModemManager is not running, disable it if necessary.
 
    Serial can be obtained using `lsusb -v -d 05c6:9008` command.
 
-6. Ensure that the device is booted in Emergency Download (EDL) mode
+5. Ensure that the device is booted in Emergency Download (EDL) mode
    (please refer to Quick Start Guide for your board). The process of
    flashing should start automatically: